REESE.  LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 


TH  E 


QHEMICAL  ANALYSIS  OF  IRON 


A  COMPLETE  ACCOUNT  OF  ALL  THE  BEST 
KNOWN  METHODS 


FOR    THE 


Analysis   of  Iron,  Steel,  Pig-iron,   Iron    Ore, 

Limestone,  Slag,   CJay,  Sand,   Coal,   Coke, 

and  Furnace   and  Producer  Gases. 


BY 

ANDREW   ALEXANDER   BLAIR, 

Graduate  United  States  Naval  Academy,  1866;  Chief  Chemist  United  States  Board  appointed  to 

Test  Iron,  Steel,  and  other  Metals,  1875  '•>  Chief  Chemist  United  States  Geological  Survey 

and  Tenth  Census;.  1880;   Member  American  Philosophical  Society,  etc. 


THIRD   EDITION. 


"VX 

0NIVERSITYJ 
^ 


PHILADELPHIA: 
B.    LIPPINCOTT    COMPANY. 

1896. 


Copyright,  1888,  by  ANDREW  ALEXANDER  BLAIR. 


Copyright,  1891,  by  ANDREW  ALEXANDER  BLAIR. 


Copyright,  1896,  by  ANDREW  ALEXANDER  BLAIR. 


TO    MY    WIFE, 


WITHOUT   WHOSE   ASSISTANCE    IT   WOULD    NEVER   HAVE 
BEEN   WRITTEN, 

THIS    VOLUME 

IS    DEDICATED. 


OF  THE 

•0NIVERSITT 


TIVERSITT 


PREFACE  TO  THE  THIRD  EDITION 


SUCH  changes  as  were  necessary  to  bring  the  methods  for 
the  determination  of  the  various  elements  in  accord  with  the 
present  state  of  the  science  have  been  made  in  this  edition. 

The  method  for  the  "  Volumetric  Determination  of  Phos- 
phorus in  Steel"  is  that  worked  out  by  the  Sub-Committee  on 
Standards  of  the  International  Steel  Standards  Committee,  and 
as  such  is  merely  tentative.  Its  publication  here  is  not  official, 
but  through  the  courtesy  of  the  committee  it  is  placed  before 
the  profession  in  the  hope  that  criticism  may  confirm  its  value 
or  point  out  its  errors.  The  modifications  in  the  method  for 
the  determination  of  sulphur  in  pig-iron  are  improvements,  but 
no  method  is  perfectly  satisfactory.  Two  new  methods  for  the 
determination  of  carbon  are  given,  and  some  modifications  of 
Volhard's  method  for  the  determination  of  manganese  in  high 
grade  manganese  ores  are  introduced. 

Many  minor  changes  have  been  made,  and  it  is  hoped  that 
this  edition  may  meet  the  same  cordial  reception  as  the  two 
former. 

LABORATORY  OF  BOOTH,  GARRETT  &  BLAIR, 
PHILADELPHIA,  September,  1896. 


PREFACE  TO  THE  SECOND   EDITION. 


IN  preparing  the  second  edition  of  this  book  I  have  tried  to 
correct  the  mistakes  that  were  apparent  in  the  first  edition,  and  to 
add  such  matter  as  the  advance  in  analytical  chemistry  seemed  to 
justify.  In  effecting  the  first  of  the  objects  I  have  been  aided  by 
such  kindly  criticism  as  the  profession  and  reviews  offered  me, 
and  in  the  second  by  the  advice  and  assistance  of  many  of  my 
fellow-workers.  Among  others  my  thanks  are  due  to  Messrs. 
Maunsel  White  and  A.  L.  Colby,  of  the  Bethlehem  Iron  Company, 
Mr.  Clemens  Jones,  of  the  Thomas  Iron  Company,  Mr.  E.  F. 
Wood,  of  the  Homestead  Steel-Works,  Mr.  T.  T.  Morrell,  of  the 
Cambria  Iron  Company,  Mr.  H.  C.  Babbitt,  of  the  Wellman  Steel 
Company,  Prof.  F.  W.  Clarke,  Chief  Chemist  U.S.  Geological 
Survey,  Mr.  J.  E.  Stead,  of  Middlesbo rough,  England,  and  Mr.  J. 
Edward  Whitfield,  of  Philadelphia. 

It  will  be  seen  that  the  "Table  of  Atomic  Weights"  has  been 
revised  ;  the  latest  and  most  reliable  values  for  the  elements  are 
given,  and  the  "Table  of  Factors"  has  been  changed  to  corre- 
spond to  these  values. 

LABORATORY  OF  BOOTH,  GARRETT  &  BLAIR, 
PHILADELPHIA,  June,  1891. 


PREFACE  TO  THE  FIRST  EDITION 


THE  various  methods  for  the  analysis  of  iron  and  steel,  as  well 
as  the  descriptions  of  special  apparatus  to  facilitate  the  perform- 
ance of  the  analytical  work,  are  so  widely  distributed  through 
transactions  of  societies,  journals,  reviews,  periodicals,  and  works 
on  general  analytical  chemistry,  that  only  the  possessor  of  a 
chemical  library  can  command  the  literature  of  the  subject.  It 
is  my  object  in  the  following  pages  to  bring  within  the  compass 
of  a  single  volume,  as  nearly  as  possible,  all  the  methods  of  real 
value  to  the  iron  analyst,  and  in  doing  this  to  give  the  credit  of 
originality  for  the  different  methods  and  improvements  to  the 
proper  persons.  In  many  cases  this  has  been  very  difficult,  and 
I  shall  be  glad  to  have  any  mistake  that  I  have  made  brought  to 
my  attention. 

This  work  presupposes  some  knowledge  of  general  and 
analytical  chemistry,  and  some  practical  experience  in  laboratory 
work  and  manipulation,  as  it  is  intended  to  be  a  guide  for  the 
student  of  iron  chemistry  only.  For  such  persons  the  details  of 
the  descriptions  of  the  methods  will,  I  hope,  often  prove  of  great 
assistance.  With  very  few  exceptions,  these  descriptions  are  the 
results  of  my  own  experience  in  the  use  of  the  methods,  and  the 
details  are  those  that  seemed  to  me  to  be  of  importance  in  their 
practical  performance.  Many  of  the  special  forms  of  apparatus 
are  of  my  own  contrivance  ;  they  have  proved  extremely  useful 
to  me,  and  I  hope  may  facilitate  in  some  cases  the  work  of  iron 
chemists,  to  whom  often  very  little  is  given  and  of  whom  very 
much  is  required. 


CONTENTS. 


PAGE 

APPARATUS II 

APPARATUS  FOR  THE  PREPARATION  OF  THE  SAMPLES n 

GENERAL  LABORATORY  APPARATUS 19 

REAGENTS 37 

ACIDS  AND  HALOGENS,  38.     GASES,  42.    ALKALIES  AND  ALKALINE  SALTS,  44.     SALTS 
OF  THE  ALKALINE  EARTHS,  50.     METALS  AND  METALLIC  SALTS,  52.     REAGENTS 
FOR   DETERMINING  PHOSPHORUS,  58. 
METHODS    FOR    THE   ANALYSIS   OF   PIG-IRON,  BAR-IRON,  AND  STEEL  .    .      59 

DETERMINATION  OF  SULPHUR.  By  evolution  as  H2S.  Absorption  by  alkaline  solution 
of  nitrate  of 'lead ',  59.  By  ammoniacal  solution  of  sulphate  of  cadmium,  62.  By  am- 
moniacal  solution  of  nitrate  of  silver,  62.  Absorption  and  oxidation  by  bromine  and 
HCl,  63.  Absorption  and  oxidation  by  permanganate  of  potassium,  64.  Absorption 
and  oxidation  by  peroxide  of  hydrogen,  65.  By  oxidation  and  solution,  65.  Special 
precautions  in  the  determination  of  S  in  pig-irons,  66.  RAPID  METHOD.  Volumetric 
determination  by  iodine,  68. 

DETERMINATION  OF  SILICON,  72.  By  solution  in  HNO3  and  HCl,  72.  By  solution  in 
HNO3  and  H2SO4,  73.  By  volatilization  in  a  current  of  chlorine  gas,  73.  RAPID 
METHOD,  77. 

DETERMINATION  OF-  SLAG  AND  OXIDES,  78.  By  solution  in  iodine,  79.  By  volatilization 
in  a  current  of  chlorine  gas,  80. 

DETERMINATION  OF  PHOSPHORUS,  81.  The  acetate  method,  81.  When  titanium  is 
present,  86.  The  molybdate  method,  89.  The  combination  method,  93.  When 
titanium  is  present,  94.  RAPID  METHODS,  95.  Volumetric  method,  95.  Direct 
weighing,  108. 

DETERMINATION  OF  MANGANESE,  109.  The  acetate  method,  109.  General  remarks  on 
the  acetate  method,  114.  The  HNO3  and  KC1O3  method  (Ford's),  115.  Steel  con- 
taining much  silicon,  117.  Pig  iron,  117.  Spiegel  and  ferro-manganese,  1 18.  RAPID 
METHODS,  1 1 8.  Volumetric  methods.  Volhard's  method,  118.  Williams' s  method, 
1 20.  Deshays's  method,  124.  Pattinson's  method  (for  Spiegel  and ferro-manganese], 
125.  The  color  method  (for  steel),  126. 

DETERMINATION  OF  CARBON,  129.  TOTAL  CARBON,  129.  Direct  combustion  in  a  cur- 
rent of  oxygen,  131.  Combustion  with  PbCrO4  and  KC1O3,  132.  Combustion  with 
CuO  in  a  current  of  oxygen,  135.  Combustion  with  Potassium  Bisulphate,  135. 
Solution  and  Oxidation  in  Sulphuric,  Chromic,  and  Phosphoric  Acids,  the  volume  of 
CO2  being  measured,  136.  Solution  and  Oxidation  in  Sulphuric,  Chromic,  and 
Phosphoric  Acids,  the  CO2  being  weighed,  140.  Volatilization  of  the  iron  in  a  cur- 
rent of  Cl,  and  subsequent  combustion  of  the  residue,  142.  Volatilization  of  the 
iron  in  a  current  of  HCl  gas,  and  subsequent  combustion  of  the  residue,  148.  Solu- 
tion in  NH4C1,  CuCl2,  nitration,  and  weighing  or  combustion  of  the  residue,  148. 

9 


10  CONTENTS. 

PAGE 

Solution  in  CuCl2  and  KC1,  filtration,  and  combustion  of  the  residue,  161.  Solution 
in  CuCh,  and  combustion  of  the  residue,  162.  Solution  in  I  or  Br,  and  combustion 
with  PbCrO4,  or  weighing,  of  the  residue,  162.  Solution  by  fused  AgCl,  and  com- 
bustion of  the  residue,  163.  Solution  of  the  iron  in  CuSO4,  filtration,  and  combus- 
tion of  the  residue  in  a  current  of  oxygen,  163.  Solution  of  the  iron  in  CuSO4,  and 
oxidation  of  the  residue  by  CrO3  -f-  H2SO4,  164.  Solution  in  dilute  HC1  by  the  aid 
of  an  electric  current,  and  combustion  of  the  residue,  165. 

DETERMINATION  OF  GRAPHITIC  CARBON 166 

DETERMINATION  OF  COMBINED  CARBON,  167.     Indirect  method,  167.     Direct  method 

(color  method),  167. 
DETERMINATION  OF  TITANIUM,  178.    By  precipitation,  178.    By  volatilization,  180. 

DETERMINATION  OF  COPPER 181 

DETERMINATION  OF  NICKEL  AND  COBALT 184 

DETERMINATION  OF  CHROMIUM  AND  ALUMINIUM,  187.  Stead's  method,  191.  Carnot's 
method,  192.  Volumetric  method  for  chromium,  193. 

DETERMINATION  OF  ARSENIC 195 

DETERMINATION  OF  ANTIMONY 196 

DETERMINATION  OF  TIN 197 

DETERMINATION  OF  TUNGSTEN 198 

DETERMINATION  OF  VANADIUM 200 

DETERMINATION  OF  NITROGEN 201 

DETERMINATION  OF  IRON 204 

METHODS    FOR   THE   ANALYSIS   OF   IRON   ORES 205 

Remarks  on  sampling,  205.  Determination  of  hygroscopic  water,  206.  Determination 
of  total  iron,  207.  Methods  for  standardizing  the  solutions,  218.  Determination  of 
FeO,  223.  Of  S,  226.  OfP2O5,  229.  OfTiO2,  231.  Of  Mn,  233.  Of  SiO2,  A12O3, 
CaO,  MgO,  MnO,  and  BaO,  238.  Of  SiO2,  247.  Separation  of  A12O3  and  Fe2O3,  248. 
Determination  of  NiO,  CoO,  ZnO,  and  MnO,  251.  Of  CuS,  PbS,  As2O6,  and  Sb2O4, 
253.  Of  the  alkalies,  255.  Of  CO2.  257.  Of  combined  water  and  carbon  in  car- 
bonaceous matter,  259.  Of  Cr2O3.  262.  Of  WO3,  264.  Of  V2O5,  264.  Of  sp.  gr., 
265. 

METHODS   FOR   THE   ANALYSIS   OF   LIMESTONE 267 

METHODS   FOR   THE   ANALYSIS   OF  CLAY        271 

METHODS   FOR   THE  ANALYSIS   OF   SLAGS 276 

METHODS   FOR  THE   ANALYSIS   OF  FIRE-SANDS 281 

METHODS    FOR   THE   ANALYSIS   OF  COAL  AND    COKE 282 

Proximate  analysis,  282.  Analysis  of  the  ash,  283.  Determination  of  sulphur,  284.  De- 
termination of  phosphoric  acid,  286. 

METHODS   FOR  THE  ANALYSIS   OF   GASES 288 

Collecting  samples,  288.  Preparation  of  the  reagents,  291.  Analysis  of  the  samples,  293. 
Determination  of  CO2,  295.  Of  O,  296.  Of  CO,  296.  Of  H,  296.  Of  CH4,  298. 
Example  of  calculation,  302. 

TABLES 303 

Table  I.  Atomic  weights  of  the  elements,  303.    Table  II.   Table  of  factors,  304.    Table 
III.   Percentages  of  P  and  P2O5  for  each  m.g.  of  Mg2P2O7,  306.    Table  IV.  Tension 
of  aqueous  vapor,  307.    Table  V.  Table  for  reducing  volumes  of  gases  to  the  normal 
state.  308. 
INDEX 315 


UNIVERSITY 

^yfO^NlA^x 

THE  CHEMICAL  ANALYSIS  OF  IRON 


APPARATUS. 

THE  speed  and  facility  with  which  results  may  be  obtained,  and  often 
the  accuracy  of  these  results,  are  dependent  upon  various  mechanical 
appliances  as  well  as  upon  the  skill  of  the  analyst.  These  appliances  will 
be  considered  under  separate  heads. 

APPARATUS  FOR  THE  PREPARATION  OF  THE  SAMPLES. 

For  crushing  iron  ores,  a  mortar  and  pestle,  such  as  are  ordinarily 
used,  have  caused  much  trouble.  In  breaking  up  hard  ores  the  wear, 
especially  on  the  pestle,  is  considerable,  and  the  particles  of  cast  iron  may 
cause  the  sample  to  yield  too  high  a  result  in  the  determination  of  metallic 
iron.  Of  course  in  non-magnetic  ores  these  particles  may  be  removed 
with  a  magnet,  but  in  the  case  of  magnetic  or  partly  magnetic  ores  this 
cannot  be  done,  and  a  hardened  steel  mortar  and  pestle  should  be  used. 
The  sample  should  be  broken  to  about  pea  size,  well  mixed,  and  quar- 
tered, this  quarter  broken  still  finer,  and  mixed  and  quartered  in  the 
same  way  until  the  resulting  portion  is  small  enough  to  be  bottled.  The 
final  grinding  can  be  best  made  on  a  chilled-iron  plate  with  a  hardened 
steel  muller.  Except  with  unusually  refractory  ores,  further  grinding  is 
unnecessary,  but  with  such  ores  the  final  grinding  must  be  in  an  agate 
mortar.  In  large  laboratories  and  where  many  ores  are  analyzed,  arrange- 

ii 


12 


APPARATUS  FOR    THE   PREPARATION  OF   THE   SAMPLES. 


ments  such  as  are  shown  in  the  accompanying  sketches  will  prove  very 
useful.  Fig.  I  shows  a  steel  mortar,  the  pestle  worked  by  power,  and 
a  chilled  plate  and  muller.  A  is  the  mortar ;  B,  a  wooden  stem  in  which 
the  pestle  fits.  The  cams  H  fit  on  the  shaft  and  raise  the  pestle  by 
means  of  the  tappets  a,  which  are  faced  with  raw  hide.  An  iron  hoop 
shrunk  on  the  mortar  has  a  ring,  in  which  is  fastened  the  low^r  block 
of  the  pulley  D  ;  the  upper  block  is  attached  to  a  traveller,  E.  When  in 
use  the  mortar  is  covered  with  a  leather  cap,  which  prevents  the  pieces 
of  ore  from  flying  out  of  the  mortar.  To  transfer  the  powdered  ore  to 


FIG.  i. 


the  chilled  plate  F,  remove  the  leather  cap,  raise  the  pestle  clear  of  the 
mortar,  and  fasten  it  up  by  a  hook  from  the  framework  to  the  tappet  a. 
Raise  the  mortar  by  pulling  the  fall  from  the  upper  block  and  fastening 
the  hook  in  its  end  into  a  ring  at  the  lower  block.  By  means  of  the 
traveller,  run  the  mortar  over  the  plate  and  turn  the  ore  out.  After 
quartering  the  sample  down,  finish  the  grinding  on  the  chilled  plate  with 
the  muller  C.  The  sheet-iron  troughs  G  serve  to  catch  any  ore  that 
falls  from  the  plate.  In  some  laboratories  a  small  Blake  crusher  is  used 


AGATE   MORTARS. 


for  crushing  the  ore,  but  it  is  more  liable  to  get  out  of  order,  and  is 
not  so  easily  cleaned  as  the  mortar  and  pestle.  Fig.  2  shows  an  arrange- 
ment for  facilitating  the  final  grinding  in  the  agate  mortar,  in  which  the 
pestle  is  rotated  by  a  Stow  flexible  shaft. 


FIG.  2. 


The  apparatus  shown  in  Fig.  3,  designed  by  Mr.  Maunsel  White, 
has  been  in  use  several  years  at  the  chemical  laboratory  of  the  Beth- 
lehem Iron  Company,  and  has  worked  very  satisfactorily.  The  power  is 
applied  from  an  overhead  countershaft  not  shown  in  the  cut.  The  lower 
portion  of  the  vertical  shaft  carries  two  horizontal  pulleys,  A  and  B; 
these  pulleys  are  connected,  as  shown,  with  the  spindle  carrying  the 
pestle  and  with  the  circular  box  D,  in  which  the  mortar  is  securely 
fastened  by  four  claw-bolts,  which  may  be  seen  in  the  drawing. 

The  piece  D  is  made  with  a  spindle  which  extends  down  into  a 
bearing  in  the  supporting  piece  H.  The  piece  H,  which  may  be  called 
a  lever,  is  secured  to  the  frame  F  by  a  bolt  which  passes  through  it, 
and  around  which  it  can  be  turned  through  an  angle  sufficient  to  per- 
mit of  the  easy  emptying  of  the  mortar  without  displacing  the  belt. 


!4  APPARATUS  FOR    THE  PREPARATION  OF   THE   SAMPLES. 

A  groove  at  the  farther  end  of  H,  as  shown,  carries  a  weighted  rod  which 
supplies  the  pressure  of  the  mortar  against  the  pestle.  The  weights  are 
made  movable  so  that  the  pressure  can  be  varied  for  special  cases. 


FIG.  3. 


The  agate  pestle  is  secured  in  a  brass  spindle  with  a  grooved  collar 
for  carrying  the  belt;  this  spindle  revolves  in  a  bored  socket  in  the 
piece  E,  and  is  secured  from  dropping  out  by  means  of  a  small  nut, 
shown  at  the  top  of  the  piece.  The  piece  E  is  connected  to  the  frame 
F  by  a  circular  bolt,  the  end  of  which  is  supplied  with  an  arm  for 
rocking  the  piece  E;  this  obtains  by  fastening  the  bolt  with  dowel-pins 
where  it  passes  through  the  piece  E  while  free  to  move  in  the  frame 
F.  The  pulley  C  is  run  from  the  countershaft,  and  revolves  a  small 
shaft  whose  end  carries  a  crank  connected  by  a  short  rod  to  the  bolt- 
arm  of  the  piece  E,  and  supplies  the  power  and  means  for  the  rocking 
motion. 

It  will  now  be  seen  that  while  the  mortar  revolves,  the  pestle, 
revolving  more  rapidly,  sweeps  across  the  face  of  the  mortar  by  the 


DRILLING-MA  CHINES. 


rocking   motion   of  the  piece   E,  thus    constantly   changing   the    material 
between  the  grinding  surfaces. 

In  taking  samples  of  iron  or  steel,  a  perfectly  clean  dry  drill  should 
be  used,  and  the  utmost  care  taken  to  prevent  grease,  oil,  or  dirt  of  any 
kind  from  getting  in  the  sample.  With  bar-iron  or  steel  the  scale  on  the 


FIG.  4. 


outside  of  the  piece  should  be  removed  as  carefully  as  possible,  the  first 

drillings  from  each  hole  thrown  away,  and  the  remainder  thoroughly  mixed 

and  placed  in  a  perfectly  clean   dry  bottle.     Fig.  4  shows  a  convenient 

form  of  drill-press  ^br  the  purpose.     A  half-inch   Morse  twist-drill  is  the 

best  for  general  use.     In  taking  samples  of  pig-iron,  the  loose  sand  should 

be  carefully  removed  from   the  outside  of  the  pig  and  a  piece  of  stout 

paper  wrapped  around  it 

to  prevent  the  sand  and  FlG- 

slag     from     the     outside 

getting    mixed   with    the 

clean  drillings,  which  are 

received    on    a    piece    of 

glazed   paper    turned    up 

at    the    edges    (Fig.    4). 

Drillings     from     pig-iron 

can    be    best    mixed    by 

rubbing  them  up  in  a  small  porcelain  mortar.     At. blast-furnaces,  to  save 

the  trouble  of  breaking  pieces  from  the  pigs  the  arrangement  shown  in 


i6 


APPARATUS  FOR    THE   PREPARATION  OF   THE    SAMPLES. 


Fig.  5  is  very  convenient,  as  half  a  pig  can  be  placed  in  the  press.  The 
framework  is  securely  bolted  to  the  table  on  which  the  press  stands,  and 
the  pig  is  secured  by  means  of  the  iron  clamps.  By  removing  the  pieces 
of  wood  under  the  pig  it  is  lowered  so  that  two  or  three  holes  can  be 
bored  in  different  parts  of  the  face  of  the  pig  to  get  an  average.  By 
taking  one  pig  from  the  first  bed,  one  from  the  last,  and  one  from  an 
intermediate  bed,  a  good  average  of  each  cast  may  be  obtained.  When 
the  ore  varies,  or  when  mixtures  of  different  ores  are  used,  these  pre- 
cautions are  very  necessary  to  get  a  sample  that  will  really  represent  an 
average  of  the  cast. 

Drillings  from   large  ingots   must  be  taken  by  means  of  an  ordinary 
brace. 

FIG.  6. 


Fig.  6  shows  an  apparatus  for  the  drilling  and  weighing  of  samples 
of  steel  for  colorimetric  carbon  or  other  rapid  determinations,  designed  by 
Mr.  Maunsel  White,  and  in  use  at  the  laboratory  of  the  Bethlehem  Iron 


SPIEGEL   MORTAR. 


•7>X 

I7 


Company.  The  drill  is  mounted  above  the  balance,  the  point  of  the 
drill  directly  overhanging  the  balance-pan.  The  piece  to  be  drilled  is 
placed  against  the  semicircular  plate  carried  by  the  two  rods  that  pass 
through  the  drill-frame  ;  on  the  rear  end  of  each  rod  is  a  coiled  spring 
which  supplies  the  pressure  necessary  for  drilling.  The  rear  ends  of  the 
rods  are  held  together  by  a  tie-piece,  which  is  connected  to  a  lever 
operated  by  the  foot,  so  that  the  rods  and  plate  can  be  forced  forward 
for  the  reception  of  the  piece  to  be  drilled. 

The  balance  is  supplied  with  an  overhead  pan  which  receives  the 
drillings  guided  to  it  through  the  funnel  fixed  in  the  top  of  the  balance- 
case  for  this  purpose.  When  the  pan  falls,  showing  that  sufficient  sample 
has  been  drilled,  pressure  is  applied  to  the  lever  by  the  foot  and  the 
piece  taken  out.  The  balance-case  rests  upon  an  iron  plate  grooved  on 
the  bottom  ;  these  grooves  engage  with  guides  screwed  to  the  table  and 
permit  the  balance-case  to  be  pulled  forward,  which  facilitates  the  cleaning 
of  the  funnel  from  all  clinging  particles.  This  operation  is  done  with  a 
camel-hair  brush  or  a  feather.  A  magnet  is  run  around  in  the  lower 
pans  to  guard  against  the  chance  of 
falling  particles  interfering  with  the 
accuracy  of  the  weights.  The  upper 
door  of  the  balance-case  is  then 
lowered  into  the  position  shown  in 
Fig.  6,  which  gives  free  access  to 
the  upper  pan  containing  the  sam- 
ple. The  sample  is  now  accurately 
weighed,  the  pan  lifted  out,  and  the 
drillings  transferred  to  the  test-tube. 

The  use  of  a  J^-inch  twist-drill  has 
been  adopted  and  found  to  give  good 
results.  The  pans  and  funnel  are 
aluminium  and  the  bearings  agate; 
the  beam  is  short,  5^  inches  in  length,  in  consequence  of  which  the 
weighing  is  done  rapidly. 

In  taking  samples  of  spiegel  or  of  white-iron,  small  clean  pieces  from 


FIG.  7. 


jg  APPARATUS  FOR    THE  PREPARATION  OF   THE   SAMPLES. 

a  number  of  pigs  should  be  taken  and  powdered  in  a  hardened  steel 
mortar.  The  mortar  shown  in  the  sketch  (Fig.  7)  is  forged  from  high 
carbon  steel,  hardened,  and  the  temper  drawn  from  the  outside.  This 
makes  the  mortar  both  hard  and  tofrgh.  The  sheet-iron  cover  prevents 
the  pieces  from  flying.  The  face  of  the  pestle  is  very  hard,  and  the 
handle  comparatively  soft,  so  that  it  will  not  break  when  struck  by  the 
hammer. 

In  taking  samples  for  analysis,  when  the  method  used  requires  the 
sample  to  be  in  a  fine  state  of  subdivision,  the  very  fine  part  of  the 
sample  should  never  be  separated  from  the  coarser  particles  by  a  sieve  or 
screen,  but  the  sample  should  be  mixed  thoroughly,  and  a  portion,  fine 
and  coarse  together,  taken  and  powdered,  so  that  all  may  pass  through 
the  sieve. 

FIG.  8. 


AIR-BA  TH. 


GENERAL  LABORATORY  APPARATUS. 

Sand-Bath  gmd  Air-Bath. 

Fig.  8  shows  a  very  convenient  form  of  sand-bath,  and  Fig.  9  an 
air-bath.  This  air-bath  is  made  from  an  ordinary  cast-iron  sink,  which 
is  supported  on  fire-bricks.  The  top  is  of  asbestos  board,  with  a  piece 


FIG.  9. 


of  sheet-iron  underneath  to  strengthen  it.  The  holes  are  large  enough 
to  take  tho  largest-sized  beakers,  while  the  smaller  beakers  are  supported 
by  asbestos  rings.  An  ordinary  gas-regulator  or  governor,  which  supplies 


20 


GENERAL   LABORATORY  APPARATUS. 


FIG.  10. 


the  gas  at  a  constant  pressure,  keeps  the  temperature  sufficiently  uni- 
form. Evaporations  may  thus  be  effected  with  great  saving  of  time  and 
with  little  danger  of  loss  by  spirting.  The  products  of  combustion  of 
the  gas  are  carried  off  by  a  separate  flue,  and  the  H2SO4  formed  does 
not  come  in  contact  with  the  solutions  in  the  baths. 

Instead  of  sand-bath  the  term  hot  plate  is  generally  used  for  this  piece 
of  apparatus,  the  surface  of  the  iron  being  kept  clean  and  free  from 
rust  by  an  occasional  coat  of  stove-polish.  Evaporations  on  the  hot 
plate  may  be  hastened  by  standing  the  beaker  containing  the  solution 
inside  another  beaker  with  the  bottom  cut  off.  Beakers  may  be  readily 

cut  in  this  way  by  starting  a  crack  and  leading 
it  around  with  a  red-hot  iron  or  glass  rod.  For 
evaporating  solutions  in  capsules  or  dishes  a 
beaker  cut  off  in  this  way  and  placed  on  a  tripod 
covered  with  wire  gauze,  as  shown  in  Fig.  10, 
may  be  used  with  great  advantage.  The  cap- 
sule is  supported  on  an  asbestos  ring,  A,  the 
bottom  being  about  J^  inch  (12  mm.)  from  the 
wire  gauze.  A  piece  of  thin  asbestos  board,  B, 
about  y^  inch  (18  mm.)  in  diameter,  rests  on 
the  gauze  and  covers  the  point  of  the  flame  of 
the  Bunsen  burner,  and,  by  throwing  the  heat 
more  on  the  sides  of  the  capsule,  tends  to  pre- 
vent spirting  when  the  solution  in  the  capsule  gets  thick  and  pasty. 


Apparatus  for  Hastening  Evaporations. 

The  little  piece  of  apparatus  shown  in  Fig.  II  was  designed  by  Mr. 
].  E.  Whitfield,  and  is  most  useful  in  hastening  evaporations.  It  consists 
of  a  platinum  tube  ^-  of  an  inch  in  diameter,  coiled  above  the  burner 
to  present  more  heating  surface,  through  which  passes  a  blast  of  air. 
As  the  platinum  tube  and  Bunsen  burner  are  both  supported  on  the 
arm  of  the  stand,  the  level  of  the  tube  may  be  made  to  accommodate 
itself  to  a  crucible  on  a  stand,  to  a  capsule  on  a  tripod  (Fig.  10),  or  to 


APPARATUS  FOR  HASTENING   EVAPORATIONS. 


21 


a  beaker  on  the  air-bath.  In  the  treatment  of  the  insoluble  residues 
from  ores  by  hydrofluoric  and  sulphuric  acids  it  is  quite  invaluable,  as 
it  not  only  hastens  the  evaporation  but  prevents  loss  by  spirting. 


FIG.  ii. 


The  blast  of  hot  air  breaks  the  bubbles  on  the  surface  of  the  liquid, 
and  when  properly  directed  it  gives  the  liquid  a  rotary  motion  that 
tends  to  throw  onto  the  sides  of  the  crucible  any  particles  of  the  liquid 
thrown  up  by  the  bubbles.  The  amount  of  heat  that  can  be  applied  to 
a  crucible  under  these  circumstances,  without  causing  loss,  is  really 
surprising.  It  is  equally  useful  when  evaporating  solutions  in  beakers  on 
the  air-bath  or  hot  plate.  In  laboratories  where  a  blast  of  air  is  always 
at  command,  the  principle  may  be  applied  in  many  ways  (or  hastening 
evaporations 

Even  a  cold  blast  of  air  from  a  drawn-out  glass  tube  directed  on 
the  surface  of  a  liquid  hastens  the  evaporation  very  materially. 


22 


GENERAL   LABORATORY  APPARATUS. 


Igniting-   Precipitates. 

For  ignitions,  a  Bunsen  burner  with  a  ring  to  regulate  the  supply 
of  air,  provided  with  an  ordinary  glass  chimney,  as  shown  in  Fig.  12, 
is  most  convenient.  By  shutting  off  the  air  entirely  a  very  low  heat 
may  be  obtained,  which  is  not  rendered  variable  by  air-currents,  and  the 
heat  of  the  full  flame  of  the  burner  is  increased  by  the  greater  draft 
caused  by  the  chimney  and  the  perfect  steadiness  of  the  flame.  By  using 
a  small  platinum  rod  or  wire  to  support  the  cover  of  the  crucible,  as 
shown  in  Fig.  12,  a  gentle  current  is  induced  in  the  crucible,  which,  while 
it  greatly  facilitates  burning  off  carbon,  is  not  sufficiently  strong  to  cause 
loss  by  carrying  off  even  the  lightest  ash.  The  crucible  may  also  be 


FIG.  12. 


FIG.   13. 


FIG.  14. 


inclined  on  its  side,  as  in  Fig.  13,  the  heat  in  this  case  being  applied 
near  the  top  of  the  crucible.  Fig.  14  shows  an  easy  method  of  fitting 
a  chimney  t;o  a  Bunsen  burner  by  means  of  a  cork  and  an  ordinary 
Argand  chimney-holder.  When  a  higher  temperature  than  that  obtain- 
able by  a  Bunsen  burner  is  required,  a  blast-lamp,  worked  by  a  foot- 
bellows,  by  a  water-blast,  or  by  a  small  blower,  is  used. 


FIL  TER-PUMPS. 


FIG.  15. 


Tripods. 

The  most  convenient  arrangement  for  heating  liquids  in  beakers, 
flasks,  etc.,  is  the  iron  tripod  (Fig.  15).  It  consists  of  a  cast-iron  ring 
with  three  legs  of  heavy  iron  wire  ^  inch 
(6  mm.)  in  diameter.  The  ring  is  covered  with 
brass  wire  gauze,  40  meshes  to  the  inch,  which 
can  be  replaced  when  it  is  burned  out,  but  which 
lasts  a  long  time.  The  vertical  height  of  the 
tripod  is  about  7^  inches  (191  mm.).  A  very 
convenient  form  of  burner  is  the  Finkner  ratchet- 
burner,  as  the  flame  can  be  raised  or  lowered 
by  means  of  the  ratchet  on  the  burner,  thus 
avoiding  the  necessity  of  reaching  back  over  the 
table  to  the  gas-cock.  As  the  air  and  gas  are  both  turned  off  at  once, 
there  is  less  danger  of  the  flame  blowing  out  when  it  is  turned  very 
low. 

Filter-Pumps. 

The  use  of  filter-pumps  for  Bunsen's  method  of  rapid  filtration  is  now 
very  general,  and  greatly  facilitates  many  operations.  The  kind  of  pump 
is  usually  determined  by  the  water-supply.  With  a  good  pressure  of 
water,  the  most  convenient  form  of  pump  is  the  injector.  Fig.  16  shows 
the  Richards'  injector  united  with  a  blast-cylinder,  by  the  use  of  which 
a  good  air-pressure  for  use  with  the  blast-lamp  may  be  obtained.  When 
the  pump  is  used  for  filtering  strong  solutions  of  HNO3  a  glass  injector 
may  be  used,  and  the  water  allowed  to  flow  at  once  into  the  sink  or 
waste-pipe.  When  the  pressure  of  water  is  not  great  enough  for  an 
injector  the  Bunsen  pump  may  be  used,  the  vacuum  obtained  of  course 
depending  on  the  amount  of  fall.  A  tank  with  a  ball-cock  attachment 
makes  this  form  of  pump  most  convenient. 

An  ordinary  air-pump  may  also  be  used  for  many  purposes,  but  of 
course  is  unsuitable  for  filtering  corrosive  liquids,  such  as  HNO3,  unless  a 
wash-bottle  containing  a  caustic  alkali  is  interposed  between  the  flask  and 


24  GENERAL   LABORATORY  APPARATUS. 

the  air-pump.     The  apparatus  shown  in  Fig.  17  will  give  a  very  good  idea 
of  an  arrangement  which  is  very  convenient  when  a  water-supply  is  not 

FIG.  16. 


available.     The  jug,  which  may  be  of  three  or  five  gallons  capacity,  serves 
as  a  reservoir.     It  connects  directly  with  the  air-pump. 

Bunsen's  Method  of  Rapid  Filtration. 

This  method  is  too  widely  known  to  make  a  detailed  description  neces- 
sary, but  some  hints  in  regard  to  the  details  may  be  useful.  In  the  first 
place,  it  is  very  difficult  to  get  good  60°  funnels,  so  that  the  little  perforated 
cones  of  platinum  to  support  the  point  of  the  filter,  which  are  sold  by  chem- 
ical dealers,  rarely  fit  the  funnel,  and  when  they  do  not  fit,  the  filters  are 


FILTERING  APPARATUS. 


apt  to  tear.     The  small  funnel  of  platinum  foil,  as  recommended  by  Bunsen, 
can  be  made  to  fit  the  funnel  better,  but  the  edges  sometimes  cut  the  filter. 

FIG.  17. 


FIG.  18. 


A  small  funnel  of  parchment  pricked  full  of  pin-holes,  and  of  the  size  and 
shape  of  the  platinum-foil  funnel,  works  very  well.  It 
is  a  mistake  to  use  too  great  a  pressure,  especially  at 
first,  and  the  filter  should  be  kept  full.  The  filtering 
flask  should  always  be  connected,  not  with  the  vacuum- 
pipe  directly,  but  with  another  flask  fitted  with  a  little 
Bunsen  valve,  which  allows  the  air  to  pass  into  the 
vacuum-pipe,  but,  in  case  of  a  sudden  stoppage  in  the 
pump,  prevents  the  back  pressure  from  entering  the  filter- 
ing-flask and  blowing  out  the  contents  of  the  funnel. 

Fig.  1 8  shows  an  arrangement  for  filtering  into  a 
beaker  instead  of  into  a  flask.  It  is  necessary  to  have  a 
glass  cover  over  the  beaker,  as  shown  in  the  sketch,  on  account  of  the  ten- 
dency the  solution  has  to  spatter,  particles  of  the  solution  being  carried  out 
of  the  beaker  in  the  current  of  air  flowing  into  the  vacuum-pipe. 


26 


GENERAL   LABORATORY  APPARATUS. 


Gooch's  Method  of  Rapid  Filtration. 

The  pierced  crucible  and  cone,  with  asbestos  felt,  devised  by  Gooch,* 
are  almost  indispensable  to  the  iron  analyst  for  the  proper  and  rapid 
execution  of  many  operations,  as  will  be  seen  by  the  frequent  references  to 
them  in  the  descriptions  of  the  methods  given  farther  on.  Fig.  19  shows 
the  crucible  and  cap,  and  Fig.  20  the  cone.  The  asbestos,  which  should  be 
of  a  soft,  silky,  flexible  fibre,  is  scraped  longitudinally  (not  cut)  to  a  fine,  soft 
down,  and  purified  by  boiling  in  strong  HC1,  and  washed  thoroughly  on  the 


FIG.  19. 


FIG.  20. 


FIG.  21. 


cone.  It  may  be  dried  and  kept  in  a  bottle.  The  perforated  crucible  is 
placed  in  one  end  of  a  piece  of  soft  rubber  tubing,  the  other  end  of  which 
is  stretched  over  the  top  of  a  funnel,  as  shown  in  Figs.  19  and  21.  The 
neck  of  the  funnel  passes  through  the  stopper  of  a  vacuum-flask.  To  pre- 
pare the  felt,  pour  a  little  of  the  prepared  asbestos  suspended  in  water  into 
the  crucible  and  attach  the  pump.  The  asbestos  at  once  assumes  the  con- 
dition of  a  firm,  compact  layer,  which  is  washed  with  ease  under  the  pressure 
of  the  pump.  After  washing  the  felt,  suck  it  dry  on  the  pump,  remove  the 
crucible,  detach  any  little  pieces  of  fibre  that  may  be  on  the  outside  of  the 
bottom  of  the  crucible,  slip  on  the  little  cap,  dry,  ignite,  and  weigh. 
Remove  the  cap,  place  the  crucible  in  the  rubber  holder,  start  the  pump 
and  pour  the  liquid  and  precipitate  to  be  filtered  into  the  crucible,  wash, 
dry,  ignite,  if  required,  cool,  and  weigh  as  before.  The  cone  is  fitted  to  a 
funnel  by  means  of  a  rubber  band  stretched  over  the  top  of  the  funnel. 


Proceedings  Am.  Acad.  Arts  and  Sciences,  1878,  p.  342;  Chem.  News,  xxxvii.  181. 


COUNTERPOISED  FILTERS.  2j 

The  pressure  of  the  pump  pulls  the  cone  down  so  that  the  overlapping  part 
of  the  band  forms  a  tight  joint  between  the  cone  and  the  upper  part  of  the 
funnel  (Fig.  22).  The  felt  is  prepared  in  the  same  manner  as  in  the  crucible. 

Fill  the  cone  with  the  asbestos  suspended  in  water, 

FIG.  22. 
start  the  pump,  press  down  the  cone  into  the  funnel, 

and,  if  necessary,  pour  in  more  of  the  asbestos,  letting 
it  run  all  around  from  the  upper  edge  of  the  cone  so 
as  to  fill  all  the  holes  and  make  a  firm,  cohesive  layer 
all  over  the  inside  of  the  perforated  portion  of  the 
cone.  Wash  it  well  with  water  and  suck  it  dry.  It 
will  then  be  ready  for  use.  The  cone  is  not  intended 
for  use  when  the  precipitate  is  to  be  weighed,  but,  as  it 
presents  a  very  large  filtering  surface,  it  is  most  useful  for  such  precipitates 
as  MnO2  precipitated  by  Ford's  method,  etc.  In  this  case,  when  the  precipi- 
tate has  been  washed  and  sucked  dry,  by  removing  the  cone  from  the  funnel 
and  carefully  separating  the  felt  from  the  sides  of  the  cone  with  a  little  piece 
of  flattened  platinum  wire,  it  may  be  removed  from  the  cone  with  the  pre- 
cipitate enclosed  in  it,  and  the  whole  mass  transferred  to  a  beaker  or  flask 
for  resolution.  The  cones  may  be  of  various  sizes  ;  for  ordinary  use,  a  cone 
1  2^  inches  (45  mm.)  in  diameter  is  very  convenient.  They  may  also  be 
used  with  a  paper  filter.  In  both  the  crucibles  and  cones  the  holes  should 
be  very  small,  and  drilled  (not  punched)  as  closely  together  as  possible. 

Counterpoised   Filters. 

The  Gooch  crucible  and  felt  are  most  useful  for  weighing  precipitates 
which  are  to  be  dried  and  not  ignited,  as  in  the  direct  weighing  of  the 
phospho-molybdate  of  ammonium.  When  they  are  not  available,  however, 
recourse  must  be  had  to  counterpoised  filters.  The  best  method  for 
preparing  and  using  them  is  as  follows  :  Take  two  washed  filters  of  the 
same  size  and  about  the  same  thickness,  fold  them  as  if  about  to  fit 
them  in  funnels,  and,  by  cutting  from  the  upper  edge  of  the  heavier  of 
the  two  with  a  pair  of  scissors,  make  them  nearly  balance.  Place  them 
between  a  pair  of  watch-glasses,  as  shown  in  Fig.  23,  dry  them  at  100° 
C,  and  allow  them  to  cool  in  a  desiccator.  Place  one  in  each  pan  of 


LIBRA?. 

OF  THE 


28  GENERAL   LABORATORY  APPARATUS. 

the  balance,  and,  handling  them   with  a  pair  of  forceps,   clip  them   until 
they  balance  exactly.     Place  each   filter  in  a  funnel,  filter  the   precipitate 
Fl  on    one  of  them,  pass    the    clear  filtrate  (not    the 

washings)  through  the  other,  and  wash  them  both 
in  the  same  manner.  Remove  them  from  the 
funnels,  turning  over  the  top  edges  of  the  filter 
containing  the  precipitate  to  prevent  any  of  the 
latter  from  falling  out,  place  them  in  a  watch- 
glass,  dry  them  at  1 00°  C.  (or  at  the  required  temperature,  whatever  it 
may  be),  cover  them  with  the  other  watch-glass,  cool  in  a  desiccator, 
place  them  on  opposite  pans  of  the  balance,  and  the  weight  added  to 
the  pan  containing  the  empty  filter,  to  make  them  balance,  is  the  weight 
of  the  precipitate. 

Filter-Paper. 

All  filter-paper  contains  more  or  less  inorganic  matter,  which  remains, 
after  burning  the  paper,  as  a  white  or  brownish  ash.  The  Swedish 
paper  with  the  water-mark  J.  H.  Munktell  leaves  the  smallest  amount 
of  ash,  and  this  ash  contains  from  35  to  65  per  cent,  silica,  besides 
ferric  oxide,  alumina,  lime,  and  magnesia  in  varying  proportions. 

Schleicher  &  Schull  prepare  some  very  pure  filters  by  washing  them 
with  HC1  and  HF1,  and  these  should  always  be  used  for  very  accurate 
work  unless  the  analyst  prepares  ashless  papers  for  himself.  The  com- 
moner kinds  of  German  paper  contain  much  larger  amounts  of  inorganic 
matter  than  the  Swedish  paper,  and  it  usually  consists  principally  of 
carbonate  of  calcium,  but  sometimes  contains  appreciable  amounts  of 
phosphates. 

Filters  of  this  kind  should  always  be  washed  with  HC1  before  they 
are  used.  They  may  be  washed  by  fitting  them  in  a  funnel,  pouring  on 
hot  HC1  and  water  (i  part  acid  to  3  parts  water),  and  washing  thoroughly 
with  hot  water.  They  may  also  be  washed  in  the  apparatus  shown  in 
Fig.  24.  It  consists  of  a  bottle  of  the  proper  size  with  the  bottom  cut 
off  with  a  hot  iron.  It  contains  a  disk  of  wood  cut  to  fit  the  shape  of 
the  bottle  and  perforated  with  a  number  of  gimlet-holes.  Fill  the  bottle 
half  full  of  cut  filters,  pour  on  a  mixture  of  HC1  and  water  (1-3),  allow 


APPARATUS  FOR    WASHING   FILTERS. 


29 


them  to  stand  about  half  an  hour,  and  wash  thoroughly  with  distilled  water. 
The  bottle  may  be  attached  to  the  vacuum-pump  and  washed  under 
pressure.  Dry  the  filters  at  a  temperature  below  100°  C.  For  prepar- 
ing ashless  filters  the  apparatus  shown  in  Fig.  25  is  used.  It  is  of  spun 
copper,  lined  with  platinum  throughout.  Over  the  vertical  tube  is  a 
perforated  platinum  disk  countersunk  to  the  level  of  the  bottom  of  the 


FIG.  24. 


FIG.  25. 


dish.  It  is  attached  to  the  pump,  and  the  filters  are  washed  first  with 
HC1  and  water  (1-3),  then  with  water  to  remove  the  lime,  then  with 
HF1  and  water  (1-3)  to  dissolve  the  silica,  and  finally  with  distilled 
water.  Swedish  filters  washed  in  this  way  are  practically  ashless,  the  ash 
from  five  filters,  each  3  inches  (75  mm.)  in  diameter,  weighing  less  than 
-j1^  mg.  Filters  may  be  cut  out,  using  tin  disks  of  the  proper  diameter  as 
patterns ;  they  may  be  bought  ready  cut,  or  they  can  be  cut  out  at  shops 
where  circular  labels  are  cut  at  very  small  cost.  The  best  way  is  to  buy 
Swedish  paper  and  a  good  tough  German  paper,  by  the  ream,  have  the 
paper  cut  into  filters  of  the  proper  sizes,  say  5^  inches  (140  mm.),  4}^ 
inches  (108  mm.),  and  3  inches  (76  mm.)  in  diameter,  and  wash  the  Swedish 
with  HC1  and  HF1  and  the  German  with  HC1.  The  ashless  filters  can 


GENERAL   LABORATORY  APPARATUS. 


be   used   for  final   filtrations   when    the   precipitate    is   to   be   ignited   and 
weighed,  and  the  German  for  all   other  work. 

Washing-Bottles. 

Figs.  26,  27,  and  28  represent  different  forms  of  washing-bottles. 
For  ordinary  use  that  represented  in  Fig.  26  is  the  best.  The  neck 
is  wrapped  with  thin  asbestos  board,  covered  with  a  piece  of  wash- 
leather  or  chamois,  which  is  sewed  to  keep  it  from  slipping.  This  is 
very  necessary  when  hot  water  is  used.  A  piece  of  soft  rubber  tubing 
at  A  is  more  pleasant  for  the  mouth  than  the  glass,  and  after  com- 
pressing the  air  in  the  flask  the  tube  can  be  grasped  with  the  teeth, 
thus  keeping  up  the  stream  of  water  for  some  time  without  effort.  It 
FIG.  26. 


FIG.  27. 


FIG.  28. 


also  prevents  the  lips  from  being  scalded  when  using  very  hot  water. 
Fig.  27  shows  a  movable  tip,  which  allows  the  stream  of  water  to  be 
directed  by  means  of  the  finger.  The  form  of  flask  shown  in  Fig.  27 
is  very  convenient  to  use  with  ammonia-water,  etc.  The  tube  a  is 
closed  with  the  index  finger,  while  the  Bunsen  valve  b  closing  as  soon 
as  the  air  is  compressed  in  the  flask  prevents  the  vapors  from  coming 
back  into  the  mouth,  and  the  stream  of  liquid  is  stopped  instantly  by 
removing  the  finger  from  a.  Fig.  28  shows  the  Berzelius  form,  which 
is  sometimes  very  useful.  The  air  is  compressed  by  blowing  into  the 
bottle  through  the  jet,  and  by  quickly  inverting  the  bottle  the  stream 


MEASURING-  GLASSES. 


of  liquid  is  forced  out  until  the  equilibrium  is  restored.  It  requires 
a  little  practice  to  use  this  form  of  bottle  easily,  but  when  the  art  is 
once  acquired  it  can  be  used  with  ammonia-water  as  well  as  pure  water, 
and  the  facility  with  which  it  can  be  moved  and  pointed  in  any  direction 
with  the  hand  makes  it  most  convenient  for  some  purposes. 

Removing  Precipitates  from  Beakers. 

A  feather  trimmed  in  the  way  shown  in  Fig.  29  may  be  used  to 
remove  particles  of  adhering  precipitates  from  beakers,  evaporating-dishes, 
etc.  A  piece  of  soft  rubber  tubing  on  the  end  of  a  piece  of  glass  rod 
or  sealed  glass  tube  is  much  more  effective  and  convenient  in  most  cases. 


FIG.  31. 


FIG.  29. 


FIG.  30. 


It  is  made  by  taking  a  short  length  of  rubber  tubing,  placing  a  little 
pure  caoutchouc  dissolved  in  chloroform  or  naphtha  in  one  end,  squeezing 
the  sides  together  between  two  pieces  of  board  (Fig.  31),  and  allowing  it 
to  remain  for  at  least  twenty-four  hours.  It  may  then  be  trimmed  down 
and  placed  on  the  end  of  a  piece  of  glass  rod  or  on  the  end  of  a  piece 
of  glass  tubing  having  the  ends  fused  together  (Fig.  30).  This  little  instru- 
ment has  acquired  the  name  of  "  policeman." 

Measuring-Glasses. 

In  adding  reagents  to  a  sample  or  to  a  solution,  measured  amounts 
should  nearly  always  be  used,  and,  as  it  is  generally  well  under 
all  circumstances  to  avoid  adding  them  from  the  bottle  direct, 
little  beakers  of  the  form  shown  in  Fig.  32  are  very  useful. 
They  can  be  graduated  and  marked  by  covering  the  side  with 
a  thin  coating  of  paraffine,  measuring  in  water  from  a  burette, 
marking  the  levels  and  amounts  in  the  paraffine  with  a  sharp- 
pointed  instrument,  and  etching  them  in  the  glass  by  filling  the  marks 


FIG.  32. 


3  2  GENERA  L   LAB  OR  A  TORY  A  PPA  RA  TUS. 

with  HF1.  After  standing  a  few  minutes  the  HF1  may  be  washed  off 
under  the  hydrant  and  the  paraffine  removed  with  hot  water.  As  the 
amounts  are  intended  to  be  only  approximate,  no  great  degree  of  care 
need  be  exercised  in  the  graduation. 

Caps  for  Reagent-Bottles. 

The  stoppers  and  lips  of  reagent-bottles  are  very  apt  to  become 
covered  with  chloride  of  ammonium,  dust,  etc.,  when  exposed  in  the 
laboratory,  and  especially  such  as  are  not  in  constant  use,  volumetric 
solutions,  stock-bottles,  etc.  It  is  well  to  keep  them  always  covered  with 
caps,  which  may  be  bought  from  the  dealers,  or  with  cracked  beakers, 
which  answer  the  purpose  nearly  as  well  in  most  cases. 

Rubber  Stoppers. 

Rubber  stoppers  are  now  generally  used  instead  of  cork.  Solid 
stoppers  should  always  be  purchased,  and  the  holes  cut  with  the  ordinary 
cork-borers.  This  is  readily  done  by  moistening  the  cork-borer  with 
water  or  alcohol.  A  little  practice  will  enable  any  one  to  do  this  with 
great  ease. 

Desiccators. 

Crucibles    should   always   be   cooled   before   weighing   in    desiccators. 

The  form  shown  in  Fig.  33  is  most  convenient.     The 
FIG.  33. 

desiccator  should  contain  fused  chloride  of  calcium. 
The  crucible  rests  on  a  small  triangle,  which  may 
be  made  of  copper  wire,  each  side  being  covered 
by  winding  a  thin  strip  of  platinum  foil  around  it 
to  prevent  the  crucible  from  coming  in  contact  with 
the  copper,  which  may  become  more  or  less  cor- 
roded. 

PLATINUM   APPARATUS. 

Crucibles. 

The  shape  of  the  crucible  is  of  considerable  importance  as  regards 
its  wearing  properties.  Fig.  34  shows  the  best  form  for  general  use. 


PLATINUM  CRUCIBLES.  33 

A  crucible  \y2  inches  (38  mm.)  high,  i^-  inches  (33^  mm.)  wide  at 
the  top,  with  a  capacity  of  20  c.c.,  and  weighing  with  the  lid  about  25 
grammes,  is  well  adapted  for  weighing  the  usual  precipi-  F|G 

tates  found  in  the  course  of  iron  analysis.  For  fusions  a 
much  larger  crucible  is  necessary:  one  i-ff  inches  (46 
mm.)  high,  i-J-|  inches  (46  mm.)  wide  on  top,  with  a  capa- 
city of  55  cc.,  and  weighing  about  60  grammes,  will  be 
found  convenient  and  serviceable.  Pure  platinum  is  the 
best  metal  for  crucibles.  The  iridium  alloy,  at  one  time  so  popular,  has 
not  been  found  to  wear  well.  It  is  stiffer  than  the  pure  metal,  but  much 
more  liable  to  crack.  The  endurance  of  a  crucible  depends  very  much 
upon  the  treatment  it  receives.  The  salts  of  easily  reduced  metals  fusing 
at  a  low  temperature,  such  as  lead,  tin,  bismuth,  antimony,  etc.,  should 
never  be  ignited  in  platinum ;  besides  these,  the  phosphoric  acid  in  some 
phosphates  is  occasionally  partly  reduced,  rendering  the  platinum  very 
brittle.  A  platinum  crucible  should  never  be  bent  out  of  shape  when 
it  can  be  avoided,  and  a  wooden  plug  exactly  the  shape  of  the  crucible 
(Fig.  35)  is  very  useful  to  straighten  it  on  when  it  has  been  bent.  It 
should  always  be  carefully  cleaned  before  use :  the  precipitate  FlQ 
last  ignited  should  be  dissolved  in  acid  if  possible,  and  the 
crucible  washed  out  with  water,  dried,  ignited,  and  cooled  in 
a  desiccator  before  weighing.  A  precipitate  of  Fe2O3  will 
sometimes  stain  a  crucible  very  badly ;  this  stain  may  be 
removed  by  allowing  the  crucible  to  stand  with  cold  HC1 
for  twelve  hours,  and  then  warming  it  for  a  short  time. 
Stains  that  are  not  removed  by  HC1  may  be  removed  by 
fusing  KHSO4  in  the  crucible,  or  by  fusing  Na2CO3  in  it,  dissolving  in 
water,  and  then  treating  the  crucible  with  HC1.  Whenever  a  crucible 
begins  to  look  dull  and  tarnished  it  should  be  cleaned  inside  and  out 
with  very  fine  sea-sand  (not  sharp  sand)  by  moistening  the  finger,  dip- 
ping it  in  the  sand,  and  rubbing  the  crucible  with  it.  This  method  of 
cleaning  decreases  the  weight  of  the  crucible  very  slightly,  the  sea-sand 
burnishing  without  cutting  the  crucible.  It  is  very  convenient  to  have 
each  crucible  and  its  cover  marked  with  a  number,  as  shown  in  Fig.  34. 

3 


34  GENERAL   LABORATORY  APPARATUS. 


Dishes. 

Fig.  36  shows  a  very  convenient  form  of  dish  for  the  determination  of  Si 
in  pig-iron,  SiO2  in  iron  ores,  etc.  It  is  3^  inches  (83  mm.)  in  diameter 

and    21/    inches    (57    mm.)    high. 
FIG.  37. 

Fig.  37,  for  such  work  as  precipi- 
tation of  Fe2O3,  etc.  It  is  5  inches 
(127  mm.)  in  diameter  and  3T5g- 
inches  (84  mm.)  high.  The  wire 
which  is  fused  into  the  top  of  the 
dish  makes  it  much  stiffer  than  it 
would  otherwise  be,  and  consequently  it  may  be  made  lighter  and  cheaper 
than  would  be  possible  without  the  wire.  The  wire  is  hammered  out  and 
helps  to  form  the  lip.  A  platinum  stirring-rod,  formed  from  a  piece  of 
seamless  tubing,  rounded  and  fused  together  at  the  ends,  is  useful  for 
many  purposes.  It  may  be  from  5/^  to  7  inches  (140  to  179  mm.)  long, 
y^  inch  (6  mm.)  in  diameter,  weighing  from  7.5  to  n  grammes. 

Spatula. 

Fig.   38   shows   a  very   convenient   and    useful    form   of  spatula.     The 

blade,  which  is   made  of  the  platinum-iridium  alloy, 

is  fused  into  a  tube  of  the  same  alloy  which  forms 

— ^~  the   handle.     The   weight    of  the   spatula   shown    in 

the  sketch  is   14  grammes,  length  6^4  inches  (165   mm.). 

Triangles   and   Tripods. 

The  triangles  for  supporting  the  crucibles  during  the  ignition  are 
shown  in  Figs.  12  and  13,  as  are  also  tripods  for  holding  the  lids,  etc. 
These  are  made  from  wire  about  -^  inch  (1.6  mm.)  diameter,  the  ends 
are  fused,  and  the  wire,  where  it  is  twisted,  has  the  parts  in  contact 
fused  together  almost  to  the  inside  of  the  triangle,  which  makes  it  much 
stiffer.  The  triangles  should  be  attached  to  the  iron  rings  of  the  sup- 
ports with  a  few  turns  of  fine  platinum  wire. 


BALANCES. 


35 


Crucible-Tongs. 

Fig.  39  shows  the  best  form  of  crucible-tongs.  The  part  from  a  to  b  is 
of  platinum,  the  straight  part  from  a  to  c  fitting  over  the  end  of  the  iron. 
The  surfaces  at  d  are  in  contact  when  the  tongs  are  closed,  and  with  this 
portion  the  lid  can  be  handled,  and  the  crucible  is  clasped  by  the  curved 
ends,  which  hold  it  firmly  without  any  danger  of  bending  the  crucible. 


FIG.  40. 


They  are  especially  useful  in  handling  a  crucible  containing  a  liquid  fusion. 
Another  form,  shown  in  Fig.  40,  is  generally  of  brass,  the  points  and  bend 
being  lined  with  platinum.  A  small  pair  of  forceps  (Fig.  41)  is  useful  for 
taking  the  crucible  from  the  desiccator  and  placing  it  on  the  balance,  the 
lid  of  the  crucible  being  slipped  a  little  to  one  side  to  allow  one  of  the 
points  of  the  forceps  to  go  inside  the  crucible. 

Balances. 

The  balance  is  one  of  the  most  important  things  in  the  equipment  of 
a  laboratory,  and  a  cheap  balance  is  nearly  always  a  very  poor  investment. 
The  quality  of  balances  has  improved  greatly  in  the  last  few  years,  and 
it  is  now  possible  to  get  a  most  admirable  instrument  of  this  kind  at  a 
comparatively  low  price.  Fig.  42  shows  a  balance  which  for  sensitiveness 
and  quickness  is  unsurpassed.  It  is  made  to  carry  up  to  200  grammes  in 
each  pan.  The  beam  is  of  aluminium,  as  are  also  the  pans.  The  stirrups 
are  of  nickel,  the  knife-edges  and  bearings  of  agate,  while  the  arrangement 
for  carrying  the  riders  (Fig.  43)  is  most  ingenious  and  effective.  It  is  of 
course  very  convenient  to  have  one  balance  for  weighing  crucibles,  etc.,  and 
another  for  weighing  samples  for  analysis.  The  balance  for  the  latter  pur- 
pose may  be  much  smaller  than  the  balance  for  the  former,  and  should  be 


GENERAL   LABORATORY  APPARATUS. 
FIG.  42. 


(D        jTol 

^aa^ 

© 

© 

provided  with  a  small  aluminium  pan  with  a  spout  (Fig.  44),  to  facilitate 
T-  the   transfer   of   samples   to 

r  IG.  43* 

flasks,  test-tubes,  etc.  This 
pan  should  have  a  coun- 
terpoise. A  pair  of  small 
forceps,  slightly  magnetized, 
may  be  used  to  advantage 

Fie;.  44- 


in  getting  exact  weights  of  steel  drillings,  and  a  camel's-hair  brush  is 
necessary  to  detach  small  particles  of  ores,  etc.,  from  the  aluminium  pan 
or  balanced  watch-glasses. 


DISTILLED    WATER. 


37 


Factor-  Weights. 

The  use  of  factor  weights  is  in  many  cases  extremely  convenient,  as 
it  does  away  with  all  calculation,  and  is  to  that  extent  time-saving  and 
valuable  in  avoiding  one  source  of  error.  Thus,  in  determining  carbon  by 
combustion  in  steel,  using  2.7273  grammes  of  the  steel,  o.i  milligramme 
of  carbonic  acid  is  equal  to  o.ooi  per  cent,  of  carbon  in  the  steel.  For 
determining  silicon  in  pig-iron  the  ^  factor  weight,  or  1.1755  grammes,  is 
very  convenient.  When  the  weight  of  SiO2  is  multiplied  by  4,  one  milli- 
gramme is  equal  to  o.oi  per  cent,  of  silicon.  Or,  for  rapid  silicon  deter- 
minations, the  Y1^  factor  weight,  0.4702  gramme,  is  used. 


REAQBNTS. 

Distilled   Water. 

When  only  a  small  amount  of  distilled  water  is  needed,  a  tin-lined 
copper  still  and  condenser,  such  as  are  furnished  by  all  dealers,  may  be 

FIG.  45. 


2  8  REAGENTS. 

used,  but  where  there  is  a  supply  of  steam,  an  arrangement  like  that 
shown  in  Fig.  45  will  be  found  most  useful.  A  is  a  tin-lined  copper 
cylinder,  with  a  dome-shaped  top,  E,  fitted  to  A  by  the  joint  shown  in 
the  sketch,  which  may  be  made  tight  by  paper  or  a  linen  rag.  Two 
perforated  shelves,  a,  a,  support  layers  of  clean  quartz-gravel  or  pieces  of 
block-tin,  which  wash  the  steam  and  prevent  dirt  from  being  carried  over 
mechanically.  The  steam  enters  at  B,  and  the  water  condensed  in  the 
cylinder  A  passes  off  through  the  pipe  C.  The  washed  steam  passes 
up  through  the  block-tin  pipe  G,  and  is  condensed  in  the  worm-tub  F. 
A  glass  worm  should  never  be  used,  as  the  water  condensed  in  it  dis- 
solves notable  amounts  of  elass. 

o 


ACIDS    AND    HALOGENS. 
Hydrochloric  Acid.     HC1.     Sp.  gr.  1.2. 

Chemically  pure  hydrochloric  acid  is  readily  obtained.  It  should  be 
free  from  chlorine,  sulphuric  and  sulphurous  acid,  arsenic,  and  fixed  salts. 
To  test  for  sulphuric  and  sulphurous  acid,  evaporate  100  c.c.  to  dryness 
with  a  little  pure  nitrate  of  potassium,  redissolve  in  water  with  a  few 
drops  of  HC1,  filter,  if  necessary,  and  add  chloride  of  barium.  To  test 
for  arsenic,  put  into  a  clean  dry  test-tube  a  few  centigrammes  of  pure 
stannous  chloride,  pour  in  carefully  6  or  8  c.c.  HC1,  and  gradually  2  or 
3  c.c.  pure  H2SO4,  shaking  the  test-tube  gently.  If  the  HC1  is  free 
from  arsenic  the  solution  remains  clear  and  colorless,  but  if  arsenic  is 
present  the  solution  becomes  yellowish,  then  brownish,  and  finally 
metallic  arsenic  is  deposited.  The  test-tube  should  be  gently  warmed  if 
no  reaction  occurs  at  first.  To  test  for  chlorine,  pour  some  of  the  acid 
into  a  solution  of  iodide  of  potassium  containing  a  little  starch  solution. 
A  blue  coloration  indicates  chlorine  or  ferric  chloride.  To  test  for 
metallic  salts,  neutralize  about  100  c.c.  of  the  acid  with  ammonia  and 
add  sulphide  of  ammonium.  To  test  for  salts  of  the  alkalies,  evaporate 
about  TOO  c.c.  of  the  acid  to  dryness,  and  test  any  residue  which  may 
remain. 


HYDROFLUORIC  ACID. 


39 


Nitric  Acid.     HNO3.     Sp.  gr.  1.41. 

Nitric  acid  should  be  free  from  nitrous  acid,  the  presence  of  which 
may  be  known  by  the  yellowish  color  it  produces.  It  may  be  freed 
from  this  gas  by  passing  a  current  of  air  through  the  acid  until  it 
becomes  colorless.  To  test  for  HC1  or  Cl,  dilute  largely  and  add  a 
solution  of  nitrate  of  silver.  To  test  for  fixed  salts,  evaporate  about 
100  c.c.  to  dryness.  The  ordinary  acid  diluted  with  an  equal  volume  of 
water  gives  the  acid  of  1.2  sp.  gr.  used  to  dissolve  steel  for  the  color 
carbon  test.  It  should  be  carefully  tested  for  Cl  or  HC1. 

Sulphuric  Acid.     H2SO4.     Sp.  gr.  1.84. 

Sulphuric  acid  should  be  colorless.  To  test  for  oxides  of  nitrogen, 
Warington*  suggests  placing  about  two  pounds  of  the  acid  in  a  bottle, 
which  it  half  fills,  and  shaking  violently.  The  air  washes  the  gases  out 
of  the  acid,  and  the  presence  of  the  oxides  of  nitrogen  may  be  detected 
by  placing  in  the  mouth  of  the  bottle  a  piece  of  filter-paper  saturated 
with  iodide  of  potassium  and  starch  solution,  which  is  colored  blue  when 
any  of  these  oxides  are  present.  To  test  for  lead,  supersaturate  some 
of  the  acid  with  ammonia  and  add  sulphide  of  ammonium. 

«  Hydrofluoric  Acid. 
The  use  of  Ceresine  bottles, 
suggested  by  Prof.  Edward 
Hart,  of  Lafayette  College,  has 
made  it  quite  possible  to  ob- 
tain pure  hydrofluoric  acid, 
but  the  crude  acid  may  be 
redistilled  in  the  laboratory 
into  platinum  bottles.  The 
crude  acid,  which  may  be  pur- 
chased from  glass  engravers 
and  etchers,  is  distilled  from 
a  platinum,  silver,  or  lead  still,  as  shown  in  Fig.  46.  The  head  of  the  still 


Crookes's  Select  Methods,  2d  ed.,  p.  494. 


40  REAGEN'IS. 

and  condensing-tube  is  of  platinum.  The  condensing-tube  runs  through 
a  copper  box  filled  with  ice,  and  a  platinum  bottle  receives  the  condensed 
acid.  Where  the  tube  comes  through  the  lower  part  of  the  box  it  is 
secured  by  a  rubber  stopper,  and  a  small  bit  of  paper  around  the  tube 
prevents  any  condensed  moisture  on  the  outside  of  the  tube  from  running 
into  the  bottle.  Before  distilling  the  acid,  put  into  it  a  few  crystals  of 
permanganate  of  potassium  and  a  few  c.c.  of  H2SO4.  The  redistilled  acid 
should  leave  no  residue  upon  evaporation. 

Acetic  Acid.     H,C2H3O2.     Sp.  gr.  1.04. 

Acetic  acid  of  the  strength  given  above  is  the  best  for  use  in  iron  analy- 
sis. It  should  give  no  residue  on  evaporation,  and  no  precipitate  upon  neu- 
tralization with  ammonia  and  the  addition  of  sulphide  of  ammonium.  It 
should  be  free  from  phosphoric  acid.  To  test  it  for  phosphoric  acid,  evapo- 
rate 100  c.c.  nearly  to  dryness,  add  a  little  magnesium  mixture  and  a  large 
excess  of  ammonia,  cool  in  ice-water,  and  stir  vigorously.  When  phos- 
phoric acid  is  present,  a  precipitate  of  ammonium  magnesium  phosphate 
will  be  obtained. 

Citric  Acid.     H3,C6H5O7,H2O. 

Citric  acid  is  easily  obtained  in  a  state  of  purity  in  the  form  of  crys- 
tals having  the  above  composition.  It  should  be  kept  in  the  solid  condi- 
tion, and  dissolved  as  needed.  It  is  soluble  in  ^  part  of  water  at  15°  C. 

Tartaric  Acid.     H2,C4H4O6. 

Tartaric  acid  is  also  easily  obtained  sufficiently  pure  for  use  in  iron 
analysis.  The  crystals  should  be  dissolved  only  as  needed.  The  only 
impurity  is  a  small  amount  of  lime.  It  is  soluble  in  y2  part  of  water  at 
15°  C. 

Oxalic  Acid.     H2,C2O4. 

Oxalic  acid  crystallizes  from  its  aqueous  solution  as  H2,C2O4,2H2O, 
soluble  in  8.7  parts  of  water  at  15°  C.  It  loses  its  water  of  hydration  very 
easily  even  at  the  ordinary  temperature  in  dry  air,  and  very  quickly  at 
100°  C. 


ACIDS.  ,[ 


Bromine.     Br. 

Bromine  is  easily  obtained  in  a  condition  sufficiently  pure  for  use  as 
a  reagent.  It  is  a  dark  brown,  extremely  corrosive  liquid,  of  sp.  gr.  2.97. 
It  is  soluble  in  about  30  parts  of  water  at  15°  C.  It  is  best  kept  in  a 
glass-stoppered  bottle  with  a  ground  cap.  As  the  aqueous  solution  is 
generally  used,  it  is  convenient  to  put  only  a  small  amount,  say  20  or  30 
c.c.,  in  the  bottle,  fill  the  bottle  nearly  full  of  cold  distilled  water,  shake  it 
up  well,  and  pour  off  the  saturated  solution  as  required.  There  usually 
remains  in  the  bottom  of  the  bottle  a  small  amount  of  impurity,  which 
is  insoluble  in  water. 

Iodine.     I. 

Iodine  is  a  metallic-looking  crystalline  solid,  of  sp.  gr.  4.95.  Resub- 
limed  iodine  is  not  sufficiently  pure  for  use,  and  must  be  redistilled  with 
great  care,  unless  it  is  used  as  iodine  dissolved  in  iodide  of  iron,  and 
filtered.  To  distil  it,  place  about  y2  kilo,  in  a  large  glass  retort  of  about 
2  litres  capacity  connected  with  an  adapter  about  1  8  inches  (456  mm.)  long 
and  3  inches  (75  mm.)  in  diameter  at  the  largest  part.  The  heat  from 
a  Bunsen  burner  turned  quite  low  will  cause  the  violet  vapors  of  iodine 
to  pass  rapidly  into  the  adapter,  where  they  will  condense  without  any 
means  being  taken  to  cool  it.  By  gently  warming  the  outside  of  the 
adapter  after  the  distillation  has  been  finished,  the  iodine  may  readily  be 
detached  in  large  masses  and  removed.  It  should  be  kept  in  a  wide- 
mouth,  glass-stoppered  bottle. 

Chlorine.     Cl. 

Chlorine  is  a  yellowish  gas  about  two  and  one-half  times  heavier  than 
air.  It  is  sparingly  soluble  in  water.  When  required  it  must  be  made. 
The  details  are  given  under  "  Determination  of  Silicon  in  Iron  and  Steel." 


Sulphurous   Acid. 

To   make   sulphurous   acid   gas,    mix   powdered   charcoal   and   strong 
sulphuric   acid    until  a  thin   paste  is  formed,  heat   the   paste   in  a  flask, 


42  REAGENTS. 

very  gently  at  first,  and  pass  the  gas  through  a  washing-bottle  containing 
a  little  water.  The  reaction  is  C+ 2H2SO4  =  CO2+ 2SO2+ 2H2O.  The 
tube  leading  from  the  flask  into  the  washing-bottle  should  have  a  bulb 
in  it  to  prevent  the  reflux  of  water  into  the  flask  in  case  of  sudden 
cooling.  Clippings  of  sheet  copper,  or  copper  turnings,  may  be  used 
instead  of  charcoal,  and  are  generally  to  be  preferred.  The  best  propor- 
tion is  250  grammes  of  copper  to  500  c.c.  of  strong  sulphuric  acid.  The 
aqueous  solution  of  the  gas  is  made  by  passing  the  washed  gas  into  dis- 
tilled water.  The  gas,  SO2,  has  a  specific  gravity  of  2.21  (air  =  i.).  i  c.c. 
of  water  at  15°  C.  dissolves  0.1353  gramme  of  SO2. 

Chromic  Acid.     CrO3. 

Chromic  anhydride  as  a  red  powder  or  in  the  form  of  scarlet  crystals 
is  easily  obtained  in  a  state  of  purity.  It  is  deliquescent,  and  dissolves 
in  a  small  quantity  of  water,  forming  a  dark  brownish-colored  liquid.  It 
may  be  made  by  pouring  i  volume  of  a  saturated  solution  of  bichromate 
of  potassium  into  \y2  volumes  of  strong  sulphuric  acid,  stirring  con- 
stantly. The  liquid  on  cooling  deposits  needles  of  chromic  anhydride, 
which  must  be  separated  from  the  mother-liquid  and  purified  by  re- 
crystallization. 

GASES. 

Carbonic  Acid  Gas.     CO2. 

The  best  form  of  generator  is  shown  in  Fig.  47.  It  was  first  sug- 
gested by  Casamajor.*  It  consists  of  a  large  tubulated  bottle,  the  bottom 
of  which  is  covered  to  the  depth  of  about  I  inch  (25  mm.)  with  buck- 
shot, on  top  of  which  rest  lumps  of  marble.  Dilute  hydrochloric  acid 
(i  acid  to  5  water)  is  admitted  through  the  tube  which  enters  at  the 
tubulure  at  the  bottom  of  the  bottle,  bending  down  so  as  to  reach  the 
bottom  of  the  bottle.  The  wash-bottle  A  contains  water.  By  blowing 
in  the  rubber  tube  attached  to  the  acid-bottle  the  acid  passes  over  into 
the  tubulated  bottle.  When  the  stopcock  K  is  closed,  the  pressure  in 

*  American  Chemist,  vi.   209 


GASES.  43 

the  tubulated  bottle  forces  the  acid  back  into  the  acid-bottle.  When  the 
acid  becomes  exhausted  and  remains  in  the  tubulated  bottle,  pour  a 
little  strong  HC1  into  the  acid-bottle  and  blow  it  over  into  the  tubulated 
bottle.  The  generated  gas  will  force  the  liquid  back  into  the  acid-bottle, 
when  it  can  be  replaced  by  fresh  acid.  A  slightly  different  form  is 
shown  in  Fig.  50. 

Sulphuretted   Hydrogen  Gas.     H2S. 

The  same  form  of  apparatus  is  used  for  generating  H2S.  Ferrous 
sulphide  is  substituted  for  marble,  but  HC1  is  used  instead  of  H2SO4,  as 
is  generally  advised,  for  the  ferrous  sulphate  formed  crystallizes  out  and 
clogs  the  apparatus. 

Hydrogen.     H. 

The  same  form  of  apparatus  as  that  used  for  CO2  and  H2S  can  be 
used  to  advantage  for  generating  hydrogen  gas.  Pieces  of  zinc,  which 
may  be  obtained  by  melting  the  zinc  and  pouring  it  in  a  sheet  about 
y^  inch  (6  mm.)  thick,  so  that  it  can  be  easily  broken,  are  to  be  used, 
and  not  granulated  zinc.  Hydrochloric  acid  is  better  than  sulphuric. 

Oxygen  Gas.     O. 

Oxygen  compressed  in  cylinders  can  be  obtained  from  most  dealers 
in  chemicals,  but  it  should  always  be  carefully  tested  before  being  used 
for  the  determination  of  carbon  in  steel  or  iron,  as  the  cylinders  are 
sometimes  filled  with  coal-gas,  and  a  cylinder  which  has  once  held  coal- 
gas  is  rarely  free  from  hydrocarbons. 

The  gas  may  be  made  on  a  small  scale  in  the  laboratory  by  care- 
fully mixing  in  a  porcelain  mortar  100  grammes  chlorate  of  potassium 
and  5  grammes  powdered  binoxide  of  manganese,  transferring  to  a  retort, 
which  the  mixture  should  not  more  than  half  fill,  and  heating  carefully 
over  a  Bunsen  burner.  The  evolved  gas  may  be  collected  in  a  gas- 
holder or  in  an  india-rubber  bag.  The  latter  is  not  to  be  recommended 
for  use  for  carbon  determinations,  as  rubber  is  very  liable  to  give  off 
hydrocarbons. 


44  RE  A  GENTS. 

ALKALIES   AND   ALKALINE    SALTS. 

Ammonia.     NH4HO. 

The  solution  of  ammonia  gas  (NH3)  commonly  used  is  of  sp.  gr.  0.88, 
and  contains  about  30  to  35  per  cent,  of  ammonia.  It  should  be  kept 
in  glass-stoppered  bottles  and  in  a  cool  place,  as  the  gas  passes  off  very 
rapidly  even  at  the  ordinary  temperature  when  open  to  the  air.  It 
should  be  colorless,  leave  no  residue  upon  evaporation,  be  free  from 
chlorides  and  sulphates,  and  give  no  precipitate  with  H2S. 

Bisulphite  of  Ammonium.     NH4HSO3. 

Bisulphite  of  ammonium  is  made  by  passing  sulphurous  acid  gas 
into  strong  ammonia  until  the  solution  becomes  yellowish  in  color  and 
smells  strongly  of  sulphurous  acid.  By  the  first  method  of  manufacture 
of  SO2  given  on  page  42,  a  large  amount  of  CO2  is  formed  at  the  same 
time,  which  is  absorbed  by  the  ammonia.  This  is  gradually  displaced 
by  the  SO2,  and  if  the  solution  is  kept  cool,  white  crystals  of  the 
neutral  sulphite,  (NH4)2SO3H2O,  are  deposited.  These  are  gradually  dis- 
solved by  the  excess  of  SO2  until  the  solution  becomes  quite  clear, 
assuming  a  yellowish  tint.  When  copper  is  used  instead  of  charcoal,  no 
CO2  is  evolved  and  no  carbonate  of  ammonium  is  formed.  By  exposure 
to  air  bisulphite  of  ammonium  is  gradually  oxidized  to  sulphate.  Old 
bisulphite  of  ammonium  always  contains  a  small  amount  of  hyposulphite, 
which  occasions  a  precipitate  of  sulphur  when  deoxidizing  solutions  of 
ferric  salts.  It  is  not  now  difficult  to  purchase  pure  bisulphite  of  ammo- 
nium, but  bisulphite  of  sodium  is  very  apt  to  contain  phosphoric  acid. 
When  made  from  strong  ammonia-water,  18  c.c.  of  bisulphite  will  deoxidize 
a  solution  of  10  grammes  of  iron  or  steel. 

Sulphide  of  Ammonium.     (NH4)2S. 

Sulphide  of  ammonium  is  made  by  saturating  strong  ammonia  with 
H2S  and  adding  an  equal  volume  of  ammonia.  The  reactions  are 

NH4HO  +  H2S  =  NH4HS  +  H2O  and 

NH4HS  +  NH4HO=-(NH4)2S+H20. 
The  solution  becomes  yellow  by  age  or  by  exposure  to  the  air. 


ALKALIES  AND   ALKALINE   SALTS.  45 

Chloride  of  Ammonium.     NH4C1. 

Chloride  of  ammonium  is  a  white,  crystalline,  anhydrous  salt,  soluble 
in  about  its  own  weight  of  water  at  100°  C.,  and  in  2.7  parts  of  water 
at  1 8°  C.  It  is  volatilized  when  heated  without  previous  fusion.  The 
salt  is  usually  purified  by  sublimation.  It  generally  contains  a  little  iron, 
but  is  free  from  other  impurities.  To  prepare  chloride  of  ammonium  for 
use  in  J.  Lawrence  Smith's  method  for  decomposition  of  silicates,  dis- 
solve it  in  boiling  water  and  evaporate  down  on  a  water-bath  or  air-bath. 
When  the  salt  begins  to  crystallize  out,  stir  vigorously.  The  crystals 
formed  will  be  very  small.  Drain  off  the  liquid  and  dry.  The  salt  can 
then  be  readily  powdered. 

Nitrate  of  Ammonium.     NH4NO3. 

Nitrate  of  ammonium  is  a  white,  crystalline  salt,  soluble  in  one-half 
its  weight  of  water  at  1 8°  C.,  and  in  much  less  at  100°  C.  When 
dissolved  in  water  it  produces  great  cold.  By  evaporation  it  loses 
ammonia  and  becomes  acid.  When  heated  it  fuses  at  108°  C.,  and  is 
decomposed  between  230°  C.  and  250°  C.  into  water  and  nitrous  oxide, 
NH4NO3=2H2O  +  N2O.  It  should  leave  no  residue  when  volatilized. 

Fluoride  of  Ammonium.     NH4P1. 

Fluoride  of  ammonium  may  be  made  by  saturating  hydrofluoric  acid  by 
ammonia.  The  salt  crystallizes  when  left  to  evaporate  over  quicklime.  It 
is  slightly  deliquescent,  and  therefore  difficult  to  keep,  as  the  solution 
attacks  glass. 

Acetate  of  Ammonium.     NH4C2H3O2. 

Acetate  of  ammonium  is  best  made  by  slightly  acidulating  ammonia 
by  acetic  acid.  One  volume  of  strong  ammonia-water  requires  about  2 
volumes  of  acetic  acid,  1.04  sp.  gr.,  to  neutralize  it.  It  is  best  to  make  it 
as  needed,  as  it  decomposes  when  kept. 

Oxalate  of  Ammonium.     (NH4)2C2O4  +  H2O. 

Oxalate  of  ammonium  is  a  white  salt,  crystallizing  in  long  prisms  united 
in  tufts.  It  is  soluble  in  20  parts  of  water  at  18°  C. 


46 


REAGENTS. 


Caustic  Soda.     NaHO. 

Fused  sodic  hydrate  purified  by  alcohol  is  sufficiently  pure  for  ordinary 
purposes.  It  forms  white  opaque  masses,  having  a  strong  affinity  for  water. 
It  dissolves  in  water  with  evolution  of  heat.  Pure  sodic  hydrate  is  prepared 
by  allowing  metallic  sodium  to  decompose  water  in  a  platinum  dish.  It 
must  be  kept  in  a  silver  or  platinum  bottle,  as  the  solution  acts  very 
rapidly  on  glass. 

Phosphate  of  Sodium  and  Ammonium.     NaNH4HPO4,4H2O. 

Phosphate  of  sodium  and  ammonium  (microcosmic  salt)  is  a  white,  crys- 
talline salt,  soluble  in  6  parts  of  cold  and  I  part  of  hot  water.  It  should 
not  be  kept  in  solution  for  any  great  length  of  time,  as  it  attacks  glass  very 
readily.  It  loses  its  water  of  crystallization  very  easily,  and  when  heated 
gives  off  its  ammonia,  leaving  pure  metaphosphate  of  sodium,  which  in  the 
fused  condition  dissolves  metallic  oxides  in  many  cases  with  the  production 
of  characteristic  colors,  which  makes  it  a  valuable  reagent  for  blow-pipe 
analysis.  It  is  easily  obtained  in  a  state  of  purity. 

Carbonate  of  Sodium.     Na2CO3. 

Carbonate  of  sodium  is  never  quite  pure.  It  always  contains  small 
amounts  of  silica,  alumina,  lime,  and  magnesia,  besides  sulphuric  acid.  It 
may  generally  be  obtained  quite  free  from  phosphoric  acid.  Every  lot 
should  be  carefully  examined  for  all  the  above  impurities,  and  the  amount 
per  gramme  noted,  so  that  the  proper  subtraction  may  be  made  in  each 
analysis.  It  is  used  in  solution  only  for  the  neutralization  of  solutions,  as 
in  the  determination  of  manganese  by  the  acetate  method,  and,  as  the  solu- 
tion attacks  glass  very  rapidly,  it  is  best  to  dissolve  the  salt  only  as  it  is 
needed. 

Nitrate  of  Sodium.     NaNO3. 

Nitrate  of  sodium  is  used  occasionally  instead  of  nitrate  of  potassium 
in  making  fusions  of  ores  containing  titanic  acid.  It  may  be  prepared 
by  acidulating  a  strong  solution  of  carbonate  of  sodium  with  nitric  acid, 
heating  until  the  water  and  excess  of  nitric  acid  are  driven  off,  and  powder- 
ing the  dry  salt. 


ALKALINE   SALTS.  ^ 

Hyposulphite  of  Sodium.     Thiosulphate  of  Sodium.      Na2S2O3-f  SH^O. 

Hyposulphite  of  sodium  is  very  soluble  in  water,  but  decomposes 
even  in  tightly-stoppered  bottles,  sulphate  of  sodium  being  formed  and 
sulphur  precipitated.  It  should,  therefore,  be  dissolved  only  as  used. 
The  ordinary  salt  of  commerce  is  sufficiently  pure  for  use. 

Acetate  of  Sodium.     NaC2H3O2  -f  3H2O. 

Crystallized  acetate  of  sodium  dissolves  in  3.9  parts  of  water  at  6°  C. 
It  is  rarely  quite  pure,  containing,  usually,  calcium  and  iron  salts,  but  it 
may  be  used  after  solution  and  filtration  for  partial  analyses,  as  in  the 
determination  of  manganese  by  the  acetate  method,  etc.  In  complete 
analyses  it  is  better  to  use  acetate  of  ammonium.  When  the  use  of 
acetate  of  sodium  is  unavoidable,  it  can  be  made  by  dissolving  C.  P.  car- 
bonate of  sodium  in  acetic  acid,  boiling  off  the  liberated  carbonic  acid, 
and  adding  acetic  acid  to  slight  acid  reaction. 

Caustic  Potassa.     KHO. 

Caustic  potassa  purified  by  solution  in  alcohol,  filtration,  and  subse- 
quent evaporation  to  dryness  and  fusion,  is  quite  pure  enough  for  all  the 
ordinary  purposes  of  iron  analysis.  An  aqueous  solution  of  1.27  sp.  gr. 
is  used  to  absorb  carbonic  acid  in  the  determination  of  carbon  in  iron 
and  steel,  in  the  determination  of  carbonic  acid  in  ores,  etc.  300  grammes 
of  fused  KHO  dissolved  in  I  litre  of  water  will  give  a  solution  of  about 
this  strength. 

Nitrite  of  Potassium.     KNO2. 

Nitrite  of  potassium  is  used  to  separate  nickel  and  cobalt.  It  is  very 
difficult  to  buy  the  pure  salt,  but  it  is  easily  made  as  follows :  Heat  I 
part  of  nitrate  of  potassium  in  an  iron  dish  until  it  is  just  fused,  then  add, 
with  constant  stirring,  2  parts  of  metallic  lead.  Raise  the  heat  slightly 
to  complete  the  oxidation  of  the  lead,  and  allow  the  mass  to  cool.  Treat 
the  mass  with  water,  filter  from  the  oxide  of  lead,  pass  CO2  through  the 
solution  to  precipitate  the  greater  part  of  the  dissolved  lead,  and  filter.  To 
the  filtrate  add  a  little  sulphide  of  ammonium  to  precipitate  the  last  traces 


48  REAGENTS. 

of  lead,  filter,  evaporate  to  dryness,  and  fuse  in  a  platinum  dish  to  decom- 
pose any  hyposulphite  that  may  have  been  formed,  and  preserve  the 
fused  salt  for  use.  Nitrite  of  potassium  is  deliquescent. 

Nitrate  of  Potassium.     KNO3. 

Nitrate  of  potassium  is  a  white,  crystalline  salt,  anhydrous,  and  soluble 
in  7^  parts  of  water  at  o°  C,  and  in  0.4  part  of  water  at  1  00°  C.  It 
melts  below  a  red  heat  to  a  colorless  liquid,  and  at  a  red  heat  gives  off 
oxygen  gas  more  or  less  contaminated  by  nitrogen,  being  converted  into 
nitrite  and  oxide  of  potassium.  The  salt  may  be  purchased  in  a  sufficient 
state  of  purity  for  all  purposes  of  iron  analysis,  but,  as  it  may  contain 
small  amounts  of  sulphuric  acid,  the  amount  should  always  be  determined 
and  the  proper  allowance  made  when  it  is  to  be  used  for  the  estimation 
of  sulphur  in  ores. 

Sulphide  of  Potassium.     K2S. 

Sulphide  of  potassium  is  made  by  passing  H2S  into  a  solution  of 
caustic  potassa  and  filtering  from  any  precipitated  alumina  or  sulphide 
of  iron.  It  is  used  instead  of  the  corresponding  ammonia-salt  when  the 
solution  contains  copper,  as  sulphide  of  copper  is  slightly  soluble  in 
sulphide  of  ammonium. 


Bichromate  of  Potassium. 
Bichromate  of  potassium  is  an  orange-colored,  anhydrous,  crystalline 
salt,  soluble  in  20  parts  of  water  at  o°  C.,  and  in  I  part  of  water  at 
1  00°  C.  It  melts  below  a  red  heat  to  a  transparent  red  liquid,  crum- 
bling to  powder  upon  cooling.  Heated  with  strong  H2SO4  it  gives  off 
about  one-sixth  its  weight  of  oxygen  gas,  the  reaction  being  K2Cr2O7  -f- 
4H2SO4=Cr2K2(SO4)4-f4H2O  +  3O.  It  is  readily  obtained  in  a  state  of 
purity,  but  should  always  be  fused  to  destroy  any  organic  matter  before 
being  used  to  determine  carbon  in  iron  or  in  ores. 

Chlorate  of  Potassium.     KC1O3. 

Chlorate   of  potassium   is   a  white,   crystalline,   anhydrous   salt.      It  is 
soluble  in  about  30  parts  of  water  at  o°  C.,  and  in  about  2  parts  at  100°  C. 


POTASSIUM  SALTS.  ^ 

It  is  readily  decomposed  by  heat,  first  into  a  mixture  of  chloride  and  per- 
chlorate  of  potassium,  a  portion  of  the  oxygen  being  set  free,  and  at  a 
higher  temperature  the  perchlorate  is  decomposed,  the  remaining  oxygen 
is  given  off  and  chloride  of  potassium  alone  remains.  It  is  easily  obtained 
in  a  sufficient  state  of  purity  for  use  in  iron  analysis.  Heated  with  nitric 
acid  it  yields  nitrate  and  perchlorate  of  potassium,  water,  chlorine,  and 
oxygen,  thus  : 


Heated  with  hydrochloric  acid  it  gives  chloride  of  potassium,  water,  and 
a  mixture  of  peroxide  of  chlorine  and  chlorine,  called  euchlorine,  thus  : 

4KC103  +  1  2HC1  =4KC1  +  6H20  +  3C1O2  +  9C1. 

Bisulphate  of  Potassium.     KHSO4. 

Bisulphate  of  potassium  is  a  white,  crystalline  salt,  soluble  in  about  one- 
half  its  weight  of  boiling  water.  A  large  amount  of  water  decomposes  it 
into  sulphate  of  potassium  and  free  sulphuric  acid  ;  even  in  the  presence  of 
a  large  excess  of  sulphuric  acid  the  neutral  salt  crystallizes  out,  leaving  free 
sulphuric  acid  in  the  solution.  Bisulphate  of  potassium  melts  at  197°  C.  ; 
at  higher  temperatures  it  gives  off  water,  leaving  the  anhydrous  salt,  and  at 
a  red  heat  it  gives  -off  sulphuric  acid,  leaving  the  neutral  sulphate.  It  is 
difficult  to  obtain  it  very  pure,  but  it  may  be  made  as  follows  :  Dissolve 
bicarbonate  of  potassium  in  water,  filter,  and  from  a  graduated  vessel  add 
H2SO4  until,  after  boiling  ofT  the  liberated  CO2,  the  solution  is  neutral,  or 
but  very  faintly  alkaline  to  test-paper.  Filter,  if  necessary,  and  to  the  fil- 
trate add  as  much  H2SO4  as  was  added  in  the  first  place  to  neutralize  the 
bicarbonate.  Boil  the  solution  down,  and  finally  fuse  the  mass  in  a  platinum 
dish.  Cool  it,  and  when  it  is  almost  ready  to  solidify  pour  it  into  another 
dish.  Break  it  up,  and  preserve  it  in  glass-stoppered  bottles. 

Iodide  of  Potassium.     KI. 

Iodide  of  potassium  is  a  white,  crystalline,  anhydrous  salt,  very  soluble 
in  water,  and  in  dissolving  it  causes  a  fall  of  temperature  in  the  solution. 
It  is  soluble  in  about  0.8  part  of  water  at  o°  C.,  and  in  0.5  part  of 


£0  REAGENTS. 

water  at  100°  C.  It  is  soluble  in  6  parts  of  alcohol  at  the  ordinary 
temperature,  and,  when  dissolved,  the  addition  of  HC1  does  not  turn  it 
brown  if  it  is  free  from  iodate.  A  solution  of  I  part  of  iodide  of 
potassium  in  2  parts  of  water  will  dissolve  2  parts  of  iodine,  but  upon 
dilution  some  of  the  iodine  is  precipitated. 

Permanganate  of  Potassium.     KMnO4, 

Permanganate  of  potassium  is  a  dark  purple-red,  anhydrous  salt, 
crystallizing  in  long  needles.  It  is  soluble  in  16  parts  of  water  at  15°  C. 
It  is  easily  obtained  very  pure,  but  the  solution  should  always  be  filtered 
through  ignited  asbestos,  as  paper  has  a  strong  reducing  action  on  it. 

Perrocyanide  of  Potassium.     K4Pe2Cy6  -f  3H2O. 

1  Ferrocyanide  of  potassium  is  a  yellow,  crystalline  salt,  soluble  in  4 
parts  of  water  at  o°  C.,  and  in  2  parts  of  water  at  100°  C.  It  is  used 
as  a  reagent  to  show  the  presence  of  ferric  salts,  which  produce  a  blue 
coloration,  caused  by  the  formation  of  ferrocyanide  of  iron  (Prussian  blue). 

Ferricyanide  of  Potassium.     K3Fe2Cy6. 

Ferricyanide  of  potassium  is  a  blood-red,  anhydrous,  crystalline  salt, 
soluble  in  about  3.1  parts  of  water  at  o°  C.,  and  in  1.3  parts  of  water  at 
100°  C.  The  dilute  solution,  like  that  of  the  ferrocyanide,  is  yellow  in 
color.  Ferrous  salts  added  to  the  solution  give  a  blue  coloration,  due 
to  the  formation  of  ferrous  ferricyanide,  while  ferric  salts  produce  no 
change  of  color.  The  ferricyanide  should  never  be  kept  in  solution. 

SALTS   OF   THE   ALKALINE    EARTHS. 

Carbonate  of  Barium.     BaCO3. 

Carbonate  of  barium  prepared  by  precipitation  is  a  soft  white  powder. 
It  is  difficult  to  obtain  it  in  a  state  of  purity,  but  it  is  easily  prepared 
by  adding  a  solution  of  carbonate  of  ammonium  to  a  clear  boiling  solu- 
tion of  chloride  of  barium,  washing  the  precipitated  carbonate  of  barium 
with  hot  water,  first  by  decantation  and  afterwards  on  a  filter.  The  car- 


ALKALIES  AND  ALKALINE   SALTS.  ^ 

bonate  of  ammonium  should,  of  course,  be  free  from  sulphate.  The 
thoroughly  washed  carbonate  of  barium  should  be  transferred  to  a  bottle 
and  shaken  up  with  water,  in  which  condition  it  is  ready  for  use.  Car- 
bonate of  barium  is  very  slightly  soluble  in  water,  requiring,  according  to 
the  different  authorities,  from  4,000  to  25,000  parts  of  water  to  dissolve 
it.  It  is  poisonous. 

Acetate  of  Barium.     Ba,(C,£lBO2)2. 

Acetate  of  barium  may  be  prepared  by  dissolving  pure  carbonate  of 
barium  in  acetic  acid.  It  crystallizes  with  I  or  3  molecules  of  water,  but 
dried  at  o°  C.,  or  exposed  to  the  air,  it  effloresces  and  yields  the  anhy- 
drous salt  as  a  white  powder.  It  is  very  soluble  in  water,  dissolving  in 
about  2  parts  of  water  at  o°  C.,  and  in  about  I  part  at  100°  C.  When 
heated  it  decomposes  into  acetone  and  carbonate  of  barium,  thus : 
Ba(C2H302)2=  C3H60  +  BaCO3. 

Chloride  of  Barium.     BaCl2,2H2O. 

Chloride  of  barium  is  a  white,  crystalline  salt,  soluble  in  about  3 
parts  of  water  at  15°  C.,  and  in  about  i}4  parts  at  100°  C.  Heated  to 
100°  C.  it  loses  its  water  of  crystallization,  yielding  the  anhydride  as  a 
white  mass,  which  melts  at  a  full  red  heat.  Chloride  of  barium  is  almost 
insoluble  in  strong  HC1.  It  is  used  almost  exclusively  for  the  determina- 
tion of  sulphuric  acid,  and  may  be  kept  in  solution  for  this  purpose. 
100  grammes  of  the  crystallized  salt  dissolved  in  I  litre  of  water  is  a 
good  proportion  to  use.  Of  this  solution  10  c.c.  will  precipitate  1.16 
grammes  of  BaSO4,  equal  to  0.4  gramme  SO3  or  0.16  gramme  S. 

Caustic  Baryta.  Hydrate  of  Barium.  BaH2O2,8H2O. 
Hydrate  of  barium  is  a  white,  crystalline  salt,  soluble  in  20  parts  of 
water  at  15°  C.,  and  in  3  parts  of  water  at  100°  C.  The  anhydride 
may  be  prepared  by  heating  nitrate  of  barium  to  redness  in  a  platinum 
crucible,  raising  the  heat  gradually  at  first  to  avoid  loss  from  frothing. 
It  attacks  platinum,  however,  at  a  high  temperature.  The  solution  has 
a  strong  affinity  for  carbonic  acid,  absorbing  it  readily  from  the  air,  the 


ij  2  REAGENTS. 

carbonate  of  barium   so  formed   causing   a   scum  on  the  surface  of  the 
solution.     The  solution  attacks  glass  very  strongly. 

Chloride  of  Calcium.     CaCl2. 

Crystallized  chloride  of  calcium  loses  all  its  water  of  crystallization 
at  200°  C,  yielding  the  white  porous  anhydrous  chloride,  which  is  very 
deliquescent.  The  anhydrous  salt  fuses  at  a  low  red  heat,  but  is  partly 
changed  to  oxide.  For  this  reason  the  fused  salt  should  never  be  used 
for  drying  CO2  in  the  determination  of  this  gas,  as  some  of  it  is  taken 
up  by  the  oxide  of  calcium.  A  solution  of  chloride  of  calcium  con- 
taining 59  parts  of  the  anhydrous  salt  to  100  parts  of  water  boils  at 
115°  C.,  a  saturated  solution  at  179.5°  C. 

Carbonate  of   Calcium.     CaCO3. 

Pure  carbonate  of  calcium,  for  use  in  Prof.  J.  Lawrence  Smith's 
method  for  the  determination  of  alkalies  in  silicates,  is  prepared  as 
follows:  Dissolve  marble  or  calcite,  free  from  magnesia,  in  dilute  HC1, 
add  an  excess  of  powdered  marble,  heat  the  solution,  and  add  some 
milk  of  lime  to  precipitate  magnesia,  phosphate  of  calcium,  etc.  Filter, 
heat  the  solution  almost  to  boiling,  and  precipitate  by  carbonate  of 
ammonium.  The  carbonate  of  calcium  formed  will  be  a  very  dense 
powder,  which  will  settle  readily  and  be  easily  washed.  Wash  thor- 
oughly, dry,  and  preserve  for  use. 

METALS  AND  METALLIC  SALTS. 

Metallic  Copper. 

Metallic  copper  absorbs  chlorine  gas  at  ordinary  temperatures,  and  is 
used  in  iron  analysis  to  absorb  any  chlorine  that  may  be  given  off  during 
the  combustion  of  the  carbonaceous  matter  liberated  by  the  action  of  sol- 
vents on  iron  and  steel.  It  is  used  in  the  form  of  drillings,  which  should 
be  taken  with  a  perfectly  dry  drill,  and  which  should  be  free  from  oil 
and  grease.  The  drillings  should  be  kept  in  a  stoppered  bottle,  and  may 
be  used  as  long  as  they  are  perfectly  bright  and  clean. 


COPPER  SALTS.  53 

Sulphate  of  Copper.     CuSO4,5H2O. 

Sulphate  of  copper  is  a  blue,  crystalline  salt,  soluble  in  2.7  parts  of 
water  at  18°  C.,  and  in  0.55  part  of  water  at  100°  C.  The  aqueous 
solution  of  the  neutral  salt  is  strongly  acid  to  litmus-paper.  The  crystals 
of  sulphate  of  copper  effloresce  on  the  surface  when  exposed  to  the  air; 
heated  to  1 00°  C.  they  lose  4  molecules  of  water,  and  when  heated  to 
200°  C.  they  lose  the  remaining  molecule.  The  anhydrous  salt  is  a  white 
saline  mass,  which  is  decomposed  at  a  bright-red  heat,  giving  off  sul- 
phurous acid  and  oxygen  and  leaving  cupric  oxide.  The  anhydrous  salt 
has  a  strong  affinity  for  water,  and  also  for  hydrochloric  acid  gas.  A 
solution  of  sulphate  of  copper  dissolves  metallic  iron,  the  copper  being 
precipitated  from  the  solution  at  the  same  time  in  a  spongy  mass. 

Anhydrous  Sulphate  of  Copper. 

The  property  anhydrous  sulphate  of  copper  possesses  of  absorbing 
hydrochloric  acid  gas  makes  it  useful  in  the  determination  of  carbon  by 
combustion,  and  it  is  best  prepared  for  this  purpose  as  follows :  Heat 
crystals  of  sulphate  of  copper,  about  the  size  of  a  coffee  bean,  in  a 
porcelain  dish  until  the  blue  color  of  the  crystals  disappears  and  they 
become  white.  Transfer  while  still  hot  to  a  dry,  glass-stoppered  bottle. 

Anhydrous  Cuprous  Chloride.     CuCl. 

To  prepare  the  granulated  salt  for  use  as  an  absorbent  of  hydrochloric 
acid  and  chlorine  in  carbon  determinations,  moisten  the  ordinary  powdered 
salt  of  commerce  in  a  porcelain  dish  and  rub  it  up  with  a  glass  rod  into 
little  lumps  about  the  size  of  a  coffee  bean.  Heat  it  gradually  until  the 
water  is  expelled  and  the  lumps,  which  will  be  dark  brown  in  color,  harden. 
Transfer  to  a  glass-stoppered  bottle. 

Cupric  Chloride.     CuCl2-J-Aq. 

To  prepare  cupric  chloride  for  use  in  dissolving  "iron  or  steel  for  the 
determination  of  carbon,  grind  up  equal  weights  of  sulphate  of  copper  and 
common  salt  in  a  porcelain  mortar,  and  pour  over  the  mixture  a  small 
amount  of  water  heated  to  5O°-6o°  C.  The  liquid  becomes  emerald-green 


54  REAGENTS. 

in  color,  and  deposits  upon  evaporation  sulphate  of  sodium.  Decant  from 
the  deposited  salt  and  evaporate  again  until  the  solution  is  reduced  to  a 
very  small  bulk.  Cool,  and  decant  from  the  remainder  of  the  sulphate  of 
sodium  and  the  excess  of  chloride  of  sodium.  By  further  evaporation  and 
cooling  the  cupric  chloride  may  be  obtained  in  the  form  of  green  crystals. 
These  crystals  are  deliquescent.  The  solution  should  be  diluted  and  filtered 
through  asbestos. 

Double  Chloride  of  Copper  and  Ammonium.     2(NH4Cl),CuCl2,2H2O. 
Double  Chloride  of  Copper  and  Potassium.     2(KCl),CuCl2,2H2O. 

The  double  chloride  of  copper  and  ammonium  is  a  bluish-green  crystal- 
line salt,  quite  soluble  in  water. 

The  double  chloride  of  copper  and  potassium  is  bluish-green  likewise 
and  more  soluble  than  the  ammonium  salt.  The  recent  experiments  of  the 
American  members  of  the  International  Steel  Standards  Committee  have 
shown  that  the  double  chloride  of  copper  and  ammonium  is  nearly  always 
impure,  from  the  presence  of  hydrocarbons  in  the  chloride  of  ammonium, 
derived  probably  from  the  gas  liquor  from  which  ammonia  salts  are  dis- 
tilled. These  hydrocarbons  unite  with  the  carbonaceous  residue  liberated 
from  steel  and  iron  in  the  process  of  determining  carbon,  and  of  course 
vitiate  the  results.  Several  recrystallizations  free  the  salt  to  a  certain 
extent  from  this  impurity.  The  use  of  the  potassium  salt  is  not  open  to 
this  objection. 

To  prepare  these  salts  proceed  as  follows:  Dissolve  107  parts  of 
chloride  of  ammonium  or  149.1  parts  of  chloride  of  potassium  and  170.3 
parts  of  crystallized  cupric  chloride  (CuCl2,2H2O)  in  water  and  crystallize 
out  the  double  salt.  Dissolve  about  300  grammes  of  the  double  salt  in 
i  litre  of  water,  filter  through  ignited  asbestos,  and  preserve  for  use  in 
glass-stoppered  bottles. 

Oxide  of  Copper.     CuO. 

Oxide  of  copper,  both  fine  and  coarse,  for  combustions  is  easily  obtained. 
It  may  be  prepared  as  follows  :  Dissolve  metallic  copper  in  nitric  acid,  evap- 
orate to  dryness  in  a  porcelain  dish,  transfer  it  to  a  Hessian  crucible,  and 


COPPER  AND   IRON  SALTS.  ^ 

heat  it  in  a  furnace  until  no  more  nitrous  fumes  are  given  off.  Keep  the 
crucible  well  covered  to  prevent  any  coal  getting  into  it,  and  avoid  raising 
the  heat  too  high,  or  the  mass  will  fuse.  Stir  it  from  time  to  time,  and 
when  finished  the  oxide  on  top  will  be  in  a  fine  powder,  while  that  in  the 
bottom  of  the  crucible  will  have  sintered.  Rub  it  up  in  a  mortar  and 
pass  through  a  fine  metal  sieve.  Keep  the  two  kinds,  fine  and  coarse, 
separate  in  glass-stoppered  bottles,  carefully  covered  to  preserve  them 

from  dust. 

Iron  Wire. 

Very  fine  soft  piano-forte  wire  is  the  best  form  of  iron  to  use  when 
standardizing  solutions  of  permanganate  or  bichromate  of  potassium  by 
metallic  iron.  Wrap  one  end  of  a  piece  of  wire,  about  2  feet  (610  mm.) 
long,  around  a  lead-pencil,  and,  using  this  as  a  handle,  draw  the  wire 
several  times  through  a  piece  of  fine  emery-cloth,  then  through  a  fold 
of  dry  filter-paper,  then,  holding  the  wire  with  the  paper,  wrap  it  around 
the  pencil.  Cut  -off  the  end  that  has  not  been  cleaned,  and  the  little 
spiral  of  wire  will  be  in  a  convenient  form  for  weighing. 


Ferrous  Sulphate. 

Ferrous  sulphate  (green  vitriol,  or  copperas)  is  a  bluish-green  crystal- 
line salt,  soluble  iru  1.64  parts  of  water  at  10°  C,  and  in  0.3  part  at  100°  C. 
It  is  insoluble  in  alcohol.  The  crystals  lose  6  molecules  of  water  when 
heated  to  114°  C.,  but  retain  the  last  molecule  even  at  280°  C.  Heated  to 
a  red  heat  the  anhydrous  sulphate  is  decomposed,  giving  off  sulphurous 
acid  and  leaving  a  basic  ferric  sulphate,  which  at  a  higher  temperature  is 
entirely  decomposed,  leaving  only  ferric  oxide.  To  prepare  the  crystals 
for  use  in  volumetric  analysis,  add  alcohol  to  the  aqueous  solution  of  the 
ferrous  sulphate,  when  the  salt  is  precipitated  as  a  bluish-white  powder. 
Filter,  wash  with  alcohol,  dry  thoroughly,  and  preserve  in  glass-stoppered 
bottles.  The  salt  prepared  in  this  way  remains  unaltered  for  a  long  time. 

Double  Sulphate  of  Iron  and  Ammonium.     FeSO4(NH4)2SO4,6H2O. 

The  double  sulphate  of  iron  and  ammonium  is  a  light  green  crystalline 
salt,  soluble  in  2.8  parts  of  water  at  16.5°  C.  It  may  be  prepared  as 


56  REAGENTS. 

follows :  Dissolve  276  grammes  of  crystallized  ferrous  sulphate  in  water, 
filter,  and  add  to  the  filtrate  a  clear  solution  of  sulphate  of  ammonium 
( (NH4)2SO4,  Glauber's  Sal  Secretum),  evaporate  down,  and  allow  the 
double  salt  to  crystallize  out.  Drain  the  crystals,  wash  slightly  with  cold 
water,  and  dry  on  blotting-paper.  When  perfectly  dry,  preserve  in  a 
glass-stoppered  bottle.  The  crystals  remain  unaltered  for  a  long  time 
even  in  moist  air.  They  contain  exactly  \  their  weight  of  metallic  iron. 

Mercurous  Nitrate.     Hg>NO3,H2O. 

To  prepare  this  salt,  pour  cold,  moderately  strong  HNO3  on  an  excess 
of  metallic  mercury,  and  when  the  violent  action  has  subsided,  pour  off 
the  acid  and  allow  the  salt  to  crystallize  out  by  the  cooling  of  the  acid. 
The  salt  is  soluble  in  a  small  amount  of  water,  but  a  large  amount  de- 
composes it  into  a  basic  salt  and  free  acid. 

Mercuric   Oxide.     HgO. 

Mercuric  oxide  is  a  light  orange-yellow  substance  when  prepared  by 
precipitation  from  a  mercuric  salt.  To  a  dilute  solution  of  mercuric 
chloride  add  a  slight  excess  of  caustic  potassa,  allow  the  precipitate  to 
settle,  wash  it  thoroughly  by  decantation  with  hot  water,  and  finally  wash 
it  into  a  glass-stoppered  bottle.  It  is  used  shaken  up  with  water. 

Chromate  of  Lead.     PbCrO4. 

Fused  chromate  of  lead  is  a  dark  brown  mass  showing  a  radiated 
structure,  and  when  powdered  it  is  dark  yellow  in  color,  very  heavy, 
and  slightly  hygroscopic.  It  is  easily  obtained  very  pure,  but  may  be 
made  as  follows :  Dissolve  acetate  of  lead  in  water,  add  a  little  acetic 
acid,  filter,  and  precipitate  by  a  solution  of  bichromate  of  potassium. 
Wash  by  decantation,  and  finally  on  linen,  dry,  and  heat  in  a  Hessian 
crucible  until  the  mass  is  just  fused.  Pour  on  a  polished  iron  slab,  grind 
in  a  clean  mortar,  and  preserve  the  powder  in  glass-stoppered  bottles, 
covered  to  exclude  dust.  Chromate  of  lead  heated  to  a  full  red  heat 
gives  off  oxygen  and  is  reduced  to  a  mixture  of  basic  chromate  of  lead 
and  oxide  of  chromium. 


LEAD  SALTS.  H? 

•>' 

Peroxide  of  Lead.     PbO2. 

Peroxide  of  lead  is  rather  difficult  to  obtain  in  a  state  of  purity;  it 
is  liable  to  contain  nitrate  of  lead  and  oxide  of  manganese.  The  latter 
element  interferes  materially  with  its  use  as  a  reagent  in  the  determina- 
tion of  manganese  by  the  color  test.  It  should  always  be  carefully  ex- 
amined by  boiling  with  dilute  nitric  acid,  and,  if  it  imparts  any  color  to 
the  solution,  must  be  promptly  rejected.  It  may  be  readily  prepared  by 
digesting  red  oxide  of  lead  in  dilute  nitric  acid,  decanting  off  the  nitrate 
of  lead,  and  washing  the  residue  thoroughly  with  hot  water.  Red  oxide 
of  lead  by  this  treatment  is  decomposed  into  protoxide  of  lead,  which 
dissolves  in  the  nitric  acid,  and  peroxide,  which  remains  insoluble.  Per- 
oxide of  lead  is  a  heavy  brown  powder,  which,  when  heated,  gives  off 
oxygen  and  is  converted  into  red  lead  or  protoxide  of  lead. 

Oxide  of  Lead  dissolved  in  Caustic  Potassa. 

Pour  a  cold  solution  of  nitrate  of  lead  into  caustic  potassa,  1.27  sp.gr., 
stirring  constantly  to  dissolve  the  oxide  of  lead,  which  precipitates.  Add 
the  nitrate  of  lead  until  a  permanent  precipitate  is  produced.  Allow  this 
to  settle,  and  siphon  the  clear  liquid  into  a  glass-stoppered  bottle.  It  is 
well  to  coat  the  stopper  with  a  little  paraffine,  to  prevent  its  sticking. 

Platinic  Chloride  Solution. 

Dissolve  platinum-foil  in  HC1,  adding  HNO3  from  time  to  time, 
evaporate  to  dry  ness  on  the  water-bath,  redissolve  in  HC1,  and  evaporate 
again  to  drive  off  the  HNO3.  Redissolve  in  water  with  the  addition  of 
a  few  drops  of  HC1,  filter,  and  preserve  in  a  bottle  the  stopper  and  neck 
of  which  are  protected  by  a  ground-glass  cap  to  prevent  any  access  of 
ammonia  to  the  solution. 

Metallic  Zinc. 

Melt  zinc,  which  should  be  as  free  as  possible  from  lead  and  iron, 
in  a  Hessian  crucible,  and  pour  it  in  a  thin  stream  from  a  height  of 
four  or  five  feet  into  a  bucket  of  cold  water,  giving  the  crucible  a  cir- 


5  8  REAGENTS. 

cular  motion  to  prevent  the  zinc  from  falling  in  exactly  the  same  place 
all  the  time.  Pour  off  the  water,  dry  the  granulated  zinc,  and  preserve 
it  in  bottles  for  use. 

Oxide  of  Zinc  in  Water. 

Emmerton*  suggests  the  following  method  of  preparing  this  reagent: 
Dissolve  ordinary  zinc  white  in  HC1,  add  the  zinc  white  until  there  is 
an  excess  which  will  not  dissolve,  then  add  a  little  bromine-water,  heat 
the  solution,  filter,  and  precipitate  the  oxide  of  zinc  by  ammonia,  being 
careful  to  avoid  an  excess.  Wash  thoroughly  by  decantation,  and  then 
wash  into  a  bottle.  Shake  the  bottle  well,  to  diffuse  the  oxide  through 
the  water,  before  using. 

REAGENTS   FOR   DETERMINING   PHOSPHORUS. 

Magnesia  Mixture. 

Dissolve  1 10  grammes  of  crystallized  chloride  of  magnesium  (MgCl2 
-f-6H2O)  or  50  grammes  of  the  anhydrous  salt  in  water,  and  filter.  Dis- 
solve 28  grammes  of  chloride  of  ammonium  in  water,  add  a  little  bro- 
mine-water and  a  slight  excess  of  ammonia,  and  filter.  Add  this  solution 
to  the  solution  of  chloride  of  magnesium,  add  enough  ammonia  to  make 
the  solution  smell  decidedly  of  ammonia,  dilute  to  about  2  litres,  transfer 
to  a  bottle,  shake  vigorously  from  time  to  time,  allow  to  stand  for 
several  days,  and  filter  into  a  small  bottle  as  required  for  use.  10  c.c. 
of  this  solution  will  precipitate  about  0.15  gramme  P2O5. 

Molybdate  Solution. 

Weigh  into  a  beaker  100  grammes  of  pure  molybdic  anhydride,  mix  it 
thoroughly  with  400  c.c.  of  cold  distilled  water  and  add  80  c.c.  of  strong 
ammonia  (0.90  sp.  gr.).  When  solution  is  complete,  filter  and  pour  the 
filtered  solution  slowly  with  constant  stirring  into  a  mixture  of  400  c.c.  of 
strong  nitric  acid  (1.42  sp.  gr.)  and  600  c.c.  of  distilled  water.  Allow  to  settle 
for  24  hours  and  filter.  A  solution  prepared  in  this  way  will  keep  for  sev- 
eral months  even  in  hot  weather  without  any  deposition  of  molybdic  acid. 

*  Trans.  Am.  Inst.  Min.  Engineers,  vol.  x.  p.  201. 


METHODS  FOR  THE  ANALYSIS 


OF 


PIG-IRON,  BAR-IRON,  AND  STEEL. 


DETERMINATION    OF    SULPHUR. 

By  Evolution  as  H2S. 

KARSTEN  was  the  first  to  suggest  dissolving  iron  or  steel  in 
HC1,  or  dilute  H2SO4,  and  collecting  the  evolved  H2S  by  ab- 
sorbing it  in  a  solution  of  a  metallic  salt.  He  recommended 
CuCl2. 

Absorption  by  Alkaline  Solution  of  Nitrate  of  Lead. 

The  apparatus,  Fig.  47,  shows  the  usual  arrangement  for 
carrying  out  the  process,  with  the  addition  of  the  generating- 
bottles  for  supplying  hydrogen  gas.  This  is  the  apparatus 
described  under  the  head  of  "  Apparatus  for  Generating  CO2," 
page  42.  The  wash-bottle  A  contains  an  alkaline  solution  of  Description 

of  the  ap- 

nitrate  of  lead,  and  is  connected  with  the  funnel-tube  by  the 
rubber  tube  B,  and  a  small  piece  of  glass  tubing,  C,  turned  at 
a  right  angle  with  one  end  drawn  down  and  covered  with  a 
short  piece  of  rubber  tubing.  This  fits  in  the  neck  of  the  bulb 
of  the  funnel-tube  and  makes  a  tight  joint.  The  analytical 
process  is  conducted  as  follows : 

Weigh  10  grammes  *  of  borings  or  drillings,  free  from  lumps, 

*  A  5-factor  weight  (6.878  grammes)  is  a  better  amount  to  take,  as,  when  the 
weight  of  BaSO4  found  is  multiplied  by  two,  each  milligramme  is  one-thousandth  of 
a  per  cent,  of  sulphur. 

59 


6o 


ANAL  YSIS   OF  IRON  AND   STEEL. 


FIG.  47. 


DETERMINATION  OF  SULPHUR.  6j 

into  the  previously  dried  flask  D,  and  close  it  with  the  rubber  Description 

of  the 

stopper  fitted  with  a  funnel-tube  and  a  delivery-tube.  The  outlet-  process, 
tube  from  the  flask  D  connects  with  the  tube  Ft  reaching  almost 
to  the  bottom  of  the  Erlenmeyer  flask  H.  In  each  of  the  flasks 
H  are  poured  about  20  or  30  c.c.  of  potassium  hydrate  solu- 
tion of  nitrate  of  lead*  and  enough  water  to  fill  them  two- 
thirds  full.  Connect  the  apparatus,  and  run  a  slow  stream  of  , 

I  estmg    the 

hydrogen  through  until  all  the  air  is  expelled,  then  close  the  ^p^atus. 
glass  stopcock  of  the  funnel-tube,  and  shut  off  the  supply  of 
hydrogen  by  closing  the  small  glass  stopcock  K.  If  the  con- 
nections are  all  tight,  the  liquid  will  not  recede  in  the  tube  F. 
When  this  is  assured,  disconnect  the  tube  C,  and  fill  the  bulb 
— which  should  be  of  about  100  c.c.  capacity — with  a  mixture 
of  50  c.c.  of  strong  HC1  and  50  c.c.  of  water.  Replace  the  tube  Ct 
turn  on  the  hydrogen,  and  open  the  stopcock  of  the  funnel-tube, 
so  as  to  allow  the  acid  to  flow  into  the  flask  D.  When  the  acid 
has  all  run  into  the  flask,  regulate  the  flow  of  the  hydrogen  so 
that  the  gas  shall  pass  through  the  solutions  in  the  flasks  H,  H1 
as  rapidly  as  possible,  and  heat  the  flask  D.  When  the  solu- 
tion in  the  flask  D  has  boiled  for  fifteen  minutes,  and  all  the 
metal  has  dissolved,  remove  the  source  of  heat  and  continue 
the  current  of  hydrogen  for  about  ten  minutes,  regulating  its 
flow  by  means  of  the  stopcock  K,  to  prevent  any  reflux  of  the 
liquid  in  H,  which  might  be  caused  by  the  cooling  of  the  flask 
D.  Shut  off  the  hydrogen,  disconnect  the  apparatus,  and  wash 
the  contents  of  the  flask  H  into  a  No.  2  Griffin's  beaker.  Un- 
less a  precipitate  of  sulphide  of  lead  appears  in  the  second  flask  Treatment 
Hr,  it  need  not  be  emptied,  but  the  same  solution  can  be  used  precipitate. 
over  again  for  the  next  analysis.  Collect  the  precipitate  in  a 
small  filter,  wash  it  once  or  twice  with  hot  water,  and,  while 
still  moist,  throw  the  filter  and  precipitate  back  into  the  beaker, 
in  which  have  been  placed  just  the  instant  before  some  powdered 


See  page  57. 


ANAL  YSIS   OF  IRON  AND  STEEL. 

KC1O3  and  from  5  to  20  c.c.  of  strong  HC1,  according  to  the 
amount  of  the  precipitate  of  lead  sulphide.  Allow  it  to  stand 
in  a  warm  place  until  the  fumes  shall  have  partly  passed  off, 
then  add  about  twice  its  volume  of  hot  water,  and  filter  into  a 
No.  I  beaker.  Wash  with  hot  water,  heat  the  filtrate  to  boiling, 
and  add  NH4HO  until  the  solution  is  slightly  alkaline  to  litmus- 
paper.  Acidulate  with  a  few  drops  of  HC1,  add  5  to  10  c.c.  of 
BaCl2  solution,*  boil  15  or  20  minutes,  and  stand  aside  for  half 
an  hour.  Filter  the  precipitate  of  BaSO4,  preferably  on  a  Gooch 
Baso4.  perforated  crucible,  wash  with  hot  water,  ignite,  and  weigh  as 
BaSO4,  which  contains  13.75  Per  cent.  S.  It  is  -always  well  to 
test  the  alkaline  filtrate  from  the  lead  sulphide  with  a  few  drops 
of  the  lead  solution,  for  it  might  happen  that  all  the  lead  would 
be  precipitated  from  the  solution  as  sulphide,  and  an  excess  of 
H2S  remain  in  the  solution  as  sulphide  of  potassium. 

The  entire  operation  described  above  can  be  performed  in 
about  two  and  a  half  hours,  and  is,  in  my  opinion,  the  most  ac- 
curate method  known  for  the  determination  of  sulphur  in  steel. 


Absorption  by  Ammoniacal  Solution  of  Sulphate  of  Cadmium. 

f.  f.  Morrell  f  passes  the  evolved  gas  into  an  ammoniacal 
solution  of  sulphate  of  cadmium.  Prepare  a  solution  of  sulphate 
of  cadmium  of  convenient  strength,  and  add  enough  ammonia  to 
redissolve  the  precipitate  and  give  a  clear  solution.  Place  this 
solution  in  the  bottles  H,  H,  and  proceed  as  usual.  Filter  the 
precipitate  of  sulphide  of  cadmium  in  a  counterpoised  filter,  wash 
with  water  containing  a  little  ammonia,  dry  at  100°  C.,  and 
weigh  as  CdS,  which  contains  22.25  Per  cent-  °f  S. 

Absorption  by  Ammoniacal  Solution  of  Nitrate  of  Silver. 
Berzelius  proposed  the  use  of  a  dilute  solution  of  nitrate  of 
silver  made  alkaline  by  ammonia.     The  method  of  procedure  is 

*  See  page  51.  f  Chem.  News,  xxviii.  229. 


DETERMINATION  OF  SULPHUR.  63 

as  follows :  Dissolve  I  gramme  of  AgNO3  in  a  small  quantity  of   Preparation 
water,  and  make  it  strongly  alkaline  with  NH4HO ;  pour  about 


two-thirds  of  the  solution  into  the  first  of  the  bottles  H,  and 
the  remainder  into  the  second,  and  fill  up  to  the  proper  level  silver- 
with  water.  Proceed  exactly  as  described  above  until  the  sul- 
phide of  silver  has  been  filtered  off  and  washed.  Dry  this  pre- 
cipitate carefully  at  a  low  temperature,  say  100°  C,  and  brush 
it  carefully  into  a  small,  dry  beaker,  returning  the  filter  to  the 
funnel.  Pour  into  the  bottles  H,  should  any  of  the  sulphide 
remain  adhering  to  the  sides,  20  or  30  c.c.  strong  HNO3,  and 
when  it  is  all  dissolved,  pour  the  acid  in  the  filter,  allowing  it 
to  run  into  the  beaker  containing  the  sulphide  of  silver,  and  Details  of 
wash  out  the  bottles  with  a  little  HNO3,  allowing  this  to  run 
over  the  filter  also.  Digest  the  sulphide  of  silver  until  it  is  all 
dissolved,  then  dilute  with  hot  water,  add  an  excess  of  HC1, 
and  filter  off  the  chloride  of  silver.  Add  a  small  amount  of 
carbonate  of  sodium,  and  evaporate  nearly  dry,  dilute,  add  a 
few  drops  of  HC1,  filter  if  necessary,  and  precipitate  as  before 
by  chloride  of  barium.  Even  when  the  sample  contains  no 
sulphur  a  slight  precipitate  of  carbide  of  silver  may  be  thrown 
down  by  the  carburetted  hydrogen  evolved  from  the  iron  or 
steel  by  the  action  of  the  acid. 

Absorption  and  Oxidation  by  Bromine  and  HCl. 

Fresenius  *  suggested  passing  the  evolved  gases  through  a  Advantage 
solution  of  bromine  in  HCl,  which  has  the  advantage  of  oxidiz-     method. 


ing  the  sulphuretted  hydrogen  at  once,  but  the  disadvantage  of 
filling  the  room  with  bromine-fumes  unless  the  apparatus  is  placed 
under  a  hood  with  a  good  draft.  It  is  necessary  when  using  this 
method  to  avoid  bringing  the  bromine-fumes  in  contact  with 
rubber  stoppers.  Instead  of  the  bottles  H,  attach  to  the  exit-tube  Description 
a  bulb-tube  of  the  shape  shown  in  Fig.  48,  containing  3  to  5  °atus.Pa 

*  Fresenius,  Zeitschrift,  xiii.  37. 


64 


ANAL  YSIS    OF  IRON  AND   STEEL. 


Details  of 
the 
method. 


FIG.   48. 


c.c.  of  bromine   and   enough   HC1  to  fill  the   bulb-tube   to    the 
marks  shown  in  the  cut.     When  the  operation  is  finished,  wash 

the  contents  of  the  bulb-tube  out  into 
a  beaker,  heat  until  the  bromine  is  all 
driven  off,  neutralize  by  NH4HO,  and 
precipitate  the  sulphuric  acid  exactly  as 
described  on  page  62.  Instead  of  neu- 
tralizing by  NH4HO,  the  HC1  solution 
may  be  evaporated  down  nearly  to  dry- 
ness  after  adding  a  little  carbonate  of 
sodium  or  the  solution  of  chloride  of 
barium;  but  repeated  experiments  have 
shown  that  sulphate  of  barium  is  prac- 
tically  insoluble  in  chloride  of  ammonium,  so  that  the  plan  of 

of  BaSO4 

in  NH4ci.  neutralizing  by  NH4HO,  being  the  shorter  and  less  troublesome, 
is  to  be  preferred. 

Absorption  and  Oxidation  by  Permanganate  of  Potassium. 

Drown  *  suggested  the  use  of  permanganate  of  potassium  solu- 
tion as  an  absorbent  and  oxidizer ;  the  process  being  carried  out 
as  follows :  Make  a  solution  of  permanganate  of  potassium,  5 
grammes  to  the  litre  of  water,  and  fill  the  bottles  H  to  their 
proper  height  with  this  liquid,  using  three  bottles,  however,  instead 
of  two,  and  proceed  with  the  operation  as  before  described,  being 
Avoid  rapid  careful  to  avoid  a  rapid  evolution  of  the  gas.  Wash  the  con- 

evolution 

of  gas.  tents  of  the  bottles  H  into  a  clean  beaker,  dissolve  any  oxide 
of  manganese  that  may  adhere  to  the  sides  of  the  bottles  in  HC1, 
add  this  to  the  solution  in  the  beaker,  and  then  add  enough  HC1 
to  decompose  the  permanganate  entirely.  Boil  until  the  solu- 
tion is  colorless,  filter  if  necessary,  and  precipitate  by  chloride 
of  barium.  Allow  it  to  stand  overnight,  filter,  wash,  ignite,  and 
weigh  the  BaSO4. 


Details  of 
the  pro- 
cess. 


Journal  Inst.  Min.  Engineers,  ii.  224. 


DETERMINATION  OF  SULPHUR.  & 

Absorption  and  Oxidation  by  Peroxide  of  Hydrogen. 

Craig  *  suggested  the  use  of  ammoniacal  solution  of  peroxide 
of  hydrogen  in  the  absorbing-bottles.     Attach  to  the  exit-tube 
of  the  flask  D  (Fig.  47)  a  nitrogen-bulb  of  the  usual  form  (Fig. 
48),  in  which  have  been  placed  4  c.c.  of  peroxide  of  hydrogen 
and  1 6  c.c.  of  ammonia,  and  proceed  as  before  directed.     When 
the  operation  is  finished,  wash  the  contents  of  the  nitrogen-bulb  Necessity 
into  a  small  beaker,  acidulate  slightly  with  HC1,  boil,  add  chlo-     deter- 
ride  of  barium,  and  determine  the  amount  of  BaSO4  as  usual. 
As  peroxide  of  hydrogen    always    contains    sulphuric   acid,  the 
amount    must  be  carefully  determined  in  each  fresh  lot  of  the     peroxide 

of  hydro- 

H2O2,  and  the  proper  correction  made  for  the  volume  used.  gen. 


By  Oxidation  and  Solution. 

Many  chemists  still  prefer  the  old  method  of  oxidizing  and  This  method 
dissolving  the  metal  and  precipitating  the  sulphuric  acid  in  the     by  many 
solution   by  chloride   of  barium.      The    details   are   as   follows : 
Treat  5  grammes  of  drillings  in  a  No.  4  Griffin's  beaker,  covered 
by  a  watch-glass  with  40  c.c.  of  strong  HNO3.     This  requires 
care,  for  drillings  of  bar-iron  and  low  steel  are  often  acted  on  so 
violently,  even  by  strong  HNO3,  as  to  cause  the  solution  to  boil 
over.     In  this  case  it  is  best  to  place  the  beaker  in  a  dish  con- 
taining a  little  cold  water  and  to  add  the  acid  gradually.     When 
all  the  acid   has  been  added  and  the  action  has   ceased,  some 
small  particles  generally  remain   undissolved,  and  their  solution 
is  effected  by  heating  the  beaker  on  the  sand-bath  and  finally 
by  adding  a  few  drops  of  HC1.     With  pig-iron  and  steel  there  Precautions 
is  usually  no  action  in  the  cold,  and  in  this  case  heat  the  beaker 
carefully  until   the   action   begins,  then    stand   the   beaker   in   a 
cooler  place,  and  if  the  action  becomes  very  violent,  stand  the     HN°8 
beaker  in  cold  water  until  it  moderates.     Very  high  carbon  steels 

*  Chem.  News,  xlvi.  199. 
5 


66  ANALYSIS   OF  IRON  AND   STEEL. 

dissolve  with  great  difficulty  even  in  boiling  acid  ;  but  the  solu- 
tion may  be  hastened  by  adding  a  few  drops  of  HC1  from  time 
to  time.  When  solution  is  complete  and  only  particles  of 
graphite  and  silica  remain  undissolved,  which  is  shown  by  the 
residue  being  entirely  flotant,  remove  the  cover,  add  a  little 
carbonate  of  sodium,  and  evaporate  the  solution  to  dryness  in 
the  air-bath.  The  addition  of  the  carbonate  of  sodium  is  to 
prevent  any  possible  loss  of  sulphuric  acid,  which  might  other- 
wise occur  by  the  decomposition  of  the  sulphate  of  iron  at  a 

Further  de-  high  temperature.  Remove  the  beaker  from  the  air-bath,  and 
when  cold  add  30  c.c.  HC1,  and  heat  until  the  oxide  of  iron  is 
dissolved,  evaporate  again  to  dryness  to  render  the  silica  insol- 
uble, redissolve  in  HC1,  evaporate  until  the  ferric  chloride  begins 
to  separate  out,  add  2  c.c.  HC1  and  a  little  water.  Filter  and 
wash,  being  careful  that  the  total  filtrate  and  washings  shall  not 
excede  100  c.c.  in  volume.  Heat  the  filtrate  to  boiling,  add 
10  c.c.  saturated  solution  of  chloride  of  barium,  and  allow  it  to 

whenig-  stand  in  the  cold  over  night.  Filter,  wash  with  a  little  very 
dpitate  dilute  HC1,  and  finally  with  cold  water;  dry,  ignite,  and  weigh 


as  BaSO4.  If  this  ignited  precipitate  is  reddish  in  color,  it  shows 
that  Fe2Q3  has  been  precipitated  with  the  BaSO4.  In  this  case 
fuse  wjth  Na2CO3,  dissolve  in  water,  filter,  acidulate  the  filtrate, 
and  precipitate  as  before.  Or,  filter  the  aqueous  solution  of  the 
fusion,  dissolve  in  HC1,  precipitate  by  ammonia,  weigh  the  Fe2O^ 
and  subtract  from  the  weight  of  BaSO4. 

Notes  and  Precautions. 

The  investigations  of  Phillips*  and  Matthewmanf  have  shown 
conclusively  that  in  many  pig-irons,  the  evolution  method  fails  to 
give  the  full  sulphur  contents.  This  seems  to  be  due  to  the 
formation  of  organic  sulphides,  probably  of  the  mercaptan  series, 
and  not  to  the  presence  of  copper  or  arsenic,  as  has  been  sup- 

*  Journal  American  Chem.  Society,  vol.  xvii.  p.  891. 

f  Journal  West  of  Scotland  Iron  and  Steel  Institute,  vol.  iii.  p.  27. 


DETERMINATION  OF  SULPHUR. 

posed.  As  those  compounds  are  quite  volatile  and  very  difficult 
to  oxidize,  some  portions  seem  to  pass  through  the  absorbing 
solutions,  while  under  certain  circumstances  other  portions 
remain  in  the  evolution  flask  with  great  persistency  and  are 
expelled  only  after  long  boiling. 

The  only  practicable  method  for  pig-irons  of  this  character, 
therefore,  is  the  oxidation  method. 

There  are  three  precautions  to  be  observed  in  using  this 
method.  I.  The  sample  should  be  dissolved  in  strong  nitric 
acid,  as,  when  dilute  nitric  acid,  or  even  aqua  regia,  is  used, 
some  sulphur  seems  to  escape  oxidation. 

2.  The   amount   of   acid    in    the   solution    from    which    the 
barium  sulphate  is  precipitated  must  be  most  carefully  regulated, 
as  well  as  the  absolute  volume  of  the  solution. 

3.  The  reagents  used  must  be  examined  for  sulphuric  acid. 
This  is  best  done  as  follows :    Measure  into  a  beaker  the  total 
amount    of   acid,    both    nitric    and    hydrochloric,    used    in    the 
determination,  add  a  little   sodium   carbonate  and  evaporate   to 
dryness.     Redissolve  in   15  c.c.  of  water  and  5   or  10  drops  of 
hydrochloric  acid,  filter,  heat  to  boiling,  add   10  c.c.  of  barium 
chloride,   boil    10   or    15    minutes,  allow   to   settle,   filter,  wash, 
ignite,  and  weigh  as  BaSO4.     The  amount  found  is  to  be  ab- 
stracted from  the  total  weight  of  BaSO4  found  in  the  sample. 

In  the  use  of  the  evolution  method  for  steels,  the  results 
obtained  vary  somewhat  with  the  solution  used  for  absorbing 
the  hydrogen  sulphide,  and  I  am  satisfied  that  the  best  absorbent 
is  the  alkaline  solution  of  lead  nitrate.  I  have  never  failed,  so 
far  as  I  know,  in  getting  correct  results  with  this  absorbent  in 
any  steel.  The  evolution  of  the  gas  should  be  as  rapid  as  pos- 
sible, as  there  seems  to  be  no  danger  of  any  hydrogen  sulphide 
passing  the  liquid  in  the  first  flask,  and  the  operation  is  naturally 
shortened.  If  the  solution  containing  the  precipitated  barium 
sulphate  is  boiled  vigorously  for  15  or  20  minutes,  it  is  not 
necessary  to  allow  it  to  stand  more  than  half  an  hour,  so  that  a 


68  ANALYSIS   OF  IRON  AND   STEEL. 

determination  can  be  made  in  two  hours,  or  two  hours  and  a 
half,  without  any  trouble. 

RAPID    METHOD. 
Volumetric  Determination  by  Iodine. 

This  method,  suggested  by  Elliott,*  involves  the  evolution  of 
the  sulphur  as  H2S,  its  absorption  in  a  solution  of  sodium  hy- 
drate, and  titration  by  iodine  in  iodide  of  potassium.  It  requires 
a  standard  solution  of  iodine,  a  standard  solution  of  hyposul- 
phite of  sodium,  a  starch  solution,  and  a  standard  solution  of 
bichromate  of  potassium. 

Iodine  Solution. 

Dissolve  6.5  grammes  pure  iodine  in  water  with  9  grammes 
iodide  of  potassium,  and  dilute  to  I  litre. 

Hyposulphite  of  Sodium  Solution. 

Dissolve  25  grammes  hyposulphite  of  sodium  in  water,  add 
2  grammes  carbonate  of  ammonium,  and  dilute  to  i  litre.  The 
carbonate  of  ammonium  retards  the  decomposition  of  the  hypo- 
sulphite of  sodium. 

Starch  Solution. 

Weigh  into  a  porcelain  or  Wedgwood  mortar  i  gramme  of 
pure  wheat  starch,  and  rub  it  to  a  thin  cream  with  water. 
Pour  it  into  150  c.c.  boiling  water,  allow  it  to  stand  until  cold, 
and  decant  the  clear  solution.  The  addition  of  10  or  15  c.c. 
glycerine  makes  the  solution  keep  better.  It  is  better,  how- 
ever, to  make  a  fresh  starch  solution  every  few  days. 

Dr.  Waller  recommends  Miiller's  suggestion  of  grinding  the 
starch  with  a  strong  solution  of  potassium  or  sodium  hydrate 
and  dissolving  in  hot  water  for  use.  It  keeps  indefinitely. 

Bichromate  of  Potassium  Solution. 

Dissolve  5  grammes  pure  bichromate  of  potassium  in  water, 
and  dilute  to  i  litre. 

*  Chem.  News,  xxiii.  61. 


RAPID  METHODS  FOR   SULPHUR.  £g 

All  these  solutions  should  be  placed  in  glass-stoppered  bottles 
and  kept  in  a  dark  place. 

Standardizing-  the  Solutions. 

Standardize  the  bichromate  solution  as  directed  in  the  "Anal- 
ysis  of  Iron   Ores."     When   bichromate  of  potassium  is  added  Reaction 
to  iodide  of  potassium  in  presence  of  free  HC1,  iodine  is  liber-     K2cr2o7is 
ated,    in   accordance   with   the    formula  K2Cr2O7  +  6KI+  I4HC1     Kiwith° 
=  8KCl+CraCl6+7HaO  +  6I,    or    i    equivalent  of    K2Cr2O7  =     eHx^sof 
294.5    liberates  6  equivalents  of  iodine  =761.  1.      Therefore,  by 
adding  to  a  solution  of  iodide  of  potassium  in  the  presence  of 
HC1  a  known  amount  of  bichromate,  we  can  calculate  the  ab- 
solute amount  of  iodine  liberated,  and  by  titrating  this  solution 
by  the  hyposulphite  solution  we  can  accurately  standardize  the 
latter.      The    reaction   which    takes    place   when   a   solution    of    Reaction  of 
hyposulphite  (thiosulphate)  of  sodium   is  acted  on  by  iodine  is     Phite  of 
2NaHS2O3  +  2!  =  2HI  +  Na2S4O6>    or   2   equivalents  of  thiosul-     ^3™. 
phate  unite  with  2  equivalents  of  iodine  to  form  hydriodic  acid 
and  tetrathionate  of  sodium.     By  adding  a  few  drops  of  starch 
solution  to  a  solution  containing  iodine,  blue  iodide  of  starch  is 
formed,    and    colors    the    solution    as    long   as    it    contains    free 
iodine.     When   enough  hyposulphite  is  added  to  a  solution  of 
this   kind  to  combine   exactly  with    the    iodine,   the   blue  color 
disappears.     Conversely,   upon  adding  a  solution  of  iodine  to  a 
solution  containing  hyposulphite  of  sodium  and  a  little  starch, 
the  sensitive  blue  color  of  the  iodide  of  starch  will   disappear 
as  fast  as  formed  until  all  the  thiosulphate  has  been  changed  to 
tetrathionate,  and   then  the  first  drop  of  iodine   in   excess  will 
change    the    solution    to   a   permanent   blue.      The    same   thing  Reaction  be- 
holds  true  as  regards  a  solution  containing  free  H2S,  the  reaction 


being  H2S+2l  =  2HI  +  S.     Proceed  therefore   as   follows:    Dis- 
solve  about   I  gramme  of  pure  iodide  of  potassium  in  300  c.c.     iodine- 
water,  add  5  c.c.  HC1,  and  then  25  c.c.  of  the  bichromate  solu- 
tion,  which  will  liberate  a  known   amount   of  iodine.     Drop  in 


70  ANALYSIS   OF  IRON  AND   STEEL. 

standard-      now  the  hyposulphite  solution   from   a  burette   until  the   iodine 
hyposui-      nearly  disappears,  add  a  few  drops  of  starch  solution,  and  con- 
tion.          tinue  the  hyposulphite   until  the   blue  color  fades   out  entirely. 
The  amount  of  iodine  being  known,  the  value  of  the  hyposul- 
phite solution  is  calculated  from  the  reading  of  the  burette.     Now 
standard-      measure  into  a  beaker  with  a  carefully  graduated  pipette  25  c.c. 
iodide1  so-    of   the    hyposulphite    solution,    dilute    to    300    c.c.,    add    a    few 
drops  of  the  starch  solution,  and  drop,  from  a  burette,  standard 
iodine  solution   until  the  blue  color  is  permanent.      The  value 
of  the  hyposulphite   solution   being   known,  that  of  the   iodine 
solution   is   readily  calculated.     An   example  will   illustrate  this  : 
illustration     Suppose  we  find  by  titration  that   I  c.c.  of  our  bichromate  solu- 

of  the  cal- 
culation of   tion    is    equal    to    .00566    gramme    metallic    iron;    then,    as    the 

ofethVealsU0e-S  reaction  is  6FeCl2+  K2Cr2O7  +  I4HC1  =  3Fe2Cl6  +  2KC1  +  Cr2Cl6 
+  7H2O,  I  equivalent  of  K2Cr2O7  =  294.5  is  equal  to  6  equiva- 
lents of  Fe=336.  Hence  336  :  294.5  =  .00566  :  .004961,  or  i 
c.c.  of  the  bichromate  solution  contains  .004961  gramme  K2Cr2O7, 
and  consequently  25  c.c.  contain  .124025  gramme  K2Cr2O7.  Then, 
as  we  saw  by  the  formula  that  294.5  parts  bichromate  liberate 
761.1  parts  iodine,  we  have  294.5  : 761.1  =.124025  :  .32052,  or  25 
c.c.  bichromate  solution  liberate  .32052  gramme  iodine.  We 
now  find  that  it  requires  25.3  c.c.  of  the  hyposulphite  solution 
to  decolorize  the  solution  made  by  adding  25  c.c.  bichromate 
solution  to  the  iodide  of  potassium ;  consequently  each  c.c.  of 
the  hyposulphite  contains  enough  NaHS2O3  to  react  with  .01267 
gramme  iodine.  We  now  measure  out  10  c.c.  of  the  hyposul- 
phite solution,  dilute  it  to  300  c.c.,  add  a  few  drops  of  starch 
solution,  and  find  that  it  requires  20.1  c.c.  of  the  iodide  solution  to 
give  the  permanent  blue  color.  Hence  20.1  c.c.  =  .1267  gramme 
iodine,  or  I  c.c.  iodide  solution  contains  .006303  gramme  iodine. 
As  the  reaction  with  H2S  is  H2S  +  2!  =  2HI  +  S,  it  requires  2 
equivalents  of  iodine  to  decompose  I  equivalent  of  H2S,  and  the 
proportion  is  2!  :  S  : :  253.7  :  32.06 : :  .006303  :  .000796,  or  I  c.c. 
iodine  is  equal  to  .000796  gramme  sulphur. 


RAPID  METHODS  FOR  SULPHUR.  n} 

The  standard  solutions  once  ready,  the  actual  determination 
of  sulphur  in  a  sample  is  very  simple.  Measure  50  c.c.  of  a 
solution  of  caustic  soda,  i.i  sp.  gr.,  free  from  sulphur,  into  the 
first  of  the  bottles  D.  The  second  need  not  be  used,  but  it  is 
a  good  plan  to  keep  a  caustic  potassa  solution  of  nitrate  of  lead  Details  of 
in  it,  and  attach  it  after  the  other,  to  be  certain  that  no  H2S  method, 
escapes  the  caustic  soda  solution.  Proceed  with  the  determina- 
tion as  directed  on  page  61,  and  when  finished  wash  the  contents 
of  the  bottle  D  into  a  beaker,  dilute  to  500  c.c.,  acidulate  with 
HC1,  add  a  few  drops  of  starch  solution,  and  titrate  with  the 
iodide  solution.  See  exactly  how  much  HC1  is  required  to 
acidulate  strongly  50  c.c.  of  the  caustic  soda  solution,  and  this 
amount  can  be  added  at  once,  so  that  no  time  need  be  lost  in 
testing  the  solution  with  litmus  before  titrating. 

Mr.  E.  F.  Wood,*  of  the  Homestead  Steel-Works,  modifies 
the  method  as  follows  :  Pass  the  evolved  gas  into  an  ammoniacal 
solution  of  sulphate  of  cadmium  instead  of  caustic  soda.  Filter, 
place  the  filter  containing  the  precipitate  of  sulphide  of  cadmium 
in  a  beaker  containing  cold  water,  add  enough  hydrochloric 
acid  to  dissolve  the  precipitate,  and  titrate  with  iodine  solution 
as  above  described. 

Mr.  Wood  thinks  that  this  method  has  several   advantages  wood's 
over  that  in  which  caustic  soda  is  used  to  absorb  the  H2S.     The     J^1  c 
hydrocarbon  gases  absorbed  by  the  alkaline  solution  are  gotten 
rid  of,  and  the  error  which  their  presence  may  produce  is  avoided; 
the  bulk  of  the  precipitate  is  an  indication  of  the  amount  of  sul- 
phur and  a  guide  to  the  proper  amount  of  hydrochloric  acid  to 
use   for   its    solution ;    and   when   the   sulphide   of    cadmium   is 
filtered  off,  only  a  small  amount  of  hydrochloric  acid  is  required, 
and  the  generation  of  heat  from  the  neutralization  of  the  alkali 
is  avoided. 

*  Communicated  to  the  author. 


ANAL  YSIS   OF  IRON  AND   STEEL. 


DETERMINATION    OF   SILICON. 

By  Solution  in  HNO3  and  HC1. 

Dissolve   5   grammes  of  drillings   in  40  c.c.  HNO3  with  the 

precautions  mentioned  on  page  65  ;   although  when  silicon  alone 

Best  strength  is  to  be  determined,  HNCX  of  1.2  sp.  gr.  may  be  used,  when,  in 

of  HN08 

most   cases,  the   solution    of  the    drillings   will    be    more    rapid. 


Remove  the  cover,  evaporate  the  solution  to  dryness  in  the  air- 

bath,  replace  the   cover,  and  raise  the  temperature  of  the  bath 

until  the  nitrate  of  iron  is  decomposed.      Remove  the   beaker 

from  the  air-bath,  allow  it  to  cool,  add  30  c.c.  HC1,  and  heat 

gradually   until   all   the  ferric   oxide  is   dissolved.      Remove  the 

cover,  and  evaporate  again  to  dryness  in  the  air-bath,  redissolve 

in  30  c.c.  HC1,  dilute  to  about   150  c.c.,  and  filter  on  an  ashless 

filter.      Detach  any  adhering   silica  from  the  sides   and  bottom 

of  the  beaker  with  a  "policeman,"   and  wash  it  out  with  cold 

water.     Wash  the  filter  first  with   dilute   HC1,  and  finally  with 

Testing         water.      Dry,   and    ignite    in    a   platinum    crucible    until    all    the 

Sio2wkh    carbon  is  burned,  weigh  the  residue  in  the  crucible,  moisten  it 

with  water,  add  i-io  drops  H2SO4,  and  enough  HF1  to  dissolve 

it   completely,    evaporate   to    dryness,    ignite,   and   weigh.      The 

difference  between  the  two  weights  is  SiO2,  which  contains  47.02 

By  fusion      per  cent,  of  Si.     In  the  absence  of  HF1,  unless  the  SiO2  is  per- 

Na2co8      fectly  white,  fuse  with   5   or  6  times  the  weight  of  Na2CO3,  dis- 

oratioT^"  s°lve  m  water,  acidulate  with   HC1,  evaporate  to   dryness  (in  a 

with  HCI.  platinum  or  porcelain  dish,  with  the  arrangement  shown  on  page 

20),  redissolve  in  HCI  and  water,  dilute,  filter,  wash,  ignite,  and 

weigh.      When   the  weight  of  Na2CO3  taken    does    not   exceed 

By  treating     2  or  3  grammes,  allow  the  crucible  to  cool  after  fusion,  and  then 

crucible      add  to   it   gradually  an    excess   of  strong    H2SO4,   heating  very 

H*so4.       slowly,  until  the  mass  is  quite  liquid  and  fumes  of  SO3  come  off. 

Allow  it  to  cool,  dissolve  in  water,  filter,  wash  well,  ignite,  and 

weigh. 


DETERMINATION  OF  SILICON. 

By  Solution  in  HNO3  and  H2SO4. 

Drown  *  has  suggested  a  method  which,  for  pig-irons,  has  Brown's 
come  into  very  general  use,  and  which  is  much  more  rapid  than 
the  other  method,  and  quite  as  exact.  Treat  I  gramme  of 
borings  in  a  platinum  or  porcelain  dish  with  20  c.c.  HNO3,  1.2 
sp.  gr.  When  all  action  has  ceased,  add  20  c.c.  of  H2SO4  (equal 
parts  acid  and  water),  and  evaporate — using  the  arrangement 
shown  on  page  20 — until  copious  fumes  of  SO3  are  given  off 
Allow  to  cool,  and  dilute  with  150  c.c.  water;  heat  carefully 
until  all  the  sulphate  of  iron  has  dissolved,  filter  hot,  wash  first 
with  dilute  HC1,  i.i  sp.  gr.,  and  then  with  hot  water,  ignite,  and 
weigh.  Treat  the  contents  of  the  crucible  with  H2SO4  and  HF1, 
evaporate  to  dryness,  ignite,  and  weigh  again.  The  difference 
between  the  two  weights  is  SiO2. 

By  Volatilization  in  a  Current  of  Chlorine  Gas. 

As  almost  all  steels  and  irons  contain  slags  of  various  com-  presence  of 
positions,  it  must  be  understood  that  the  SiO2  obtained  by  the     ^onTnd 
methods  above  given  is  the  total  SiO2,  comprising  any  SiO2  that     steeK 
may  be  present   m   the   admixed   slag,  as  well    as  that  formed 
from  the  Si   present   in  the   metal.      The  volatilization   method  Separation 
separates   the   two.       The   process    suggested   by    Drown,f   and     sio^ 
worked  out  independently  two  years  later  by  Watts,!  is  as  fol- 
lows :    Fig.  49  shows  the  general  arrangement  of  the  apparatus.   Description 
The  large  flask  contains  binoxide  of  manganese  in  lumps.     The 
bottle  above  it  contains  strong  common   HC1,  which  runs  into 
the  flask  through  a  siphon-tube  extending  almost  to  the  bottom. 
The    flask    stands    in    a    dish    containing   water,    which    can    be 
heated    by    the    burner    under   the   tripod.     The    evolution-tube 
from    the   flask    has   a   stopcock,   and   connects   with    the   three 
bulb-tubes  on  the  stand,  the  first  containing  water,  the  second 

*  Jour.  Inst.  Min.  Engineers,  vii.  346.  f  Ibid.,  viii.  508. 

%  Chem.  News,  xlv.  279. 


74 


ANAL  YSIS   OF  IRON  AND   STEEL. 


DETERMINATION  OF  SILICON.  j^ 

pumice-stone,  and  the  third  pumice  saturated  with  strong  H2SO4. 
The  outlet-tube  from  the  latter  leads  into  the  porcelain  or  glass 
tube  in  the  furnace.  This  tube  contains  small  lumps  of  char-  Purification 
coal  or  gas  carbon,  kept  in  position  by  loosely-fitting  plugs  of  fr0mo. 
asbestos,'  and  occupying  about  8  inches  (200  mm.)  in  the  middle 
of  the  tube.  The  outlet-tube  from  this  connects  with  the 
drying-tubes  on  the  second  stand,  which  contain  pumice  moist- 
ened with  strong  H2SO4.  The  outlet  from  the  second  drying- 
tube  connects  with  the  glass  combustion-tube,  which  leads 
through  the  second  furnace,  and  is  bent  at  a  right  angle  where 
it  is  connected  with  the  large  tubes,  half  filled  with  water.  The 
apparatus  being  in  order,  *  start  a  slow  current  of  chlorine  Details  of 
through  the  apparatus  by  blowing  HC1  from  the  bottle  into  the  method. 
flask  and  filling  the  dish  in  which  the  latter  stands  with  water. 
Light  a  low  light  under  the  dish,  and  open  the  stopcock  wide 
enough  to  allow  a  very  slow  current  to  bubble  through  the 
bulbs.  Light  the  burners  of  the  first  furnace  so  that  the  tube  is 
heated  to  dull  redness.  When  the  apparatus  is  full  of  chlorine, 
weigh  i  gramme  of  pig-iron,  or  3  grammes  of  steel,  into  a 
porcelain  boat  about  3  inches  long,  distributing  the  drillings 
evenly  along  the  bottom  of  the  boat.  Remove  the  stopper  at 
the  rear  end  of  the  second  tube  and  insert  the  boat  to  about 
the  centre.  Replace  the  stopper,  and  continue  the  current  of 
chlorine  in  the  cold  for  ten  or  fifteen  minutes  to  make  sure  that 
no  oxygen  remains  in  the  tube,  then  light  the  burner  under  the 
forward  end  of  the  boat.  The  heat  must  be  just  sufficient  to 


volatilize  the  ferric  chloride,  which  should  condense  in  the 
cooler  part  of  the  tube,  and  the  current  of  gas  should  be  slow 
enough  to  prevent  any  ferric  chloride  from  being  carried  for- 
ward into  the  water-tubes  or  any  loss  of  carbon  from  the  boat. 


*  All  the  stoppers  used  should  be  of  rubber  coated  with  paraffine  on  the  ends,  or 
of  asbestos,  and  where  glass  tubes  are  joined  together  with  rubber  the  ends  of  the 
glass  tubes  should  be  brought  into  close  contact. 


7  6  ANALYSIS   OF  IRON  AND   STEEL. 

When  the  fumes  of  ferric  chloride  begin  to  come  off  more 
slowly,  light  the  next  burner,  and  continue  until  all  the  burners 
under  the  boat  are  lighted,  maintaining  the  heat  until  the  fumes 
of  ferric  chloride  cease.  The  tube  for  the  entire  length  occupied 
by  the  boat  should  be  at  a  dull  red  heat.  Should  the  condensed 
ferric  chloride  at  any  time  choke  the  tube  so  as  to  prevent  the 
passage  of  the  gas,  heat  that  part  of  the  tube  gently  with  a 
spirit-lamp,  so  as  to  drive  the  ferric  chloride  a  little  farther 
along  the  tube.  When  the  fumes  of  ferric  chloride  are  no  longer 
given  off  from  the  boat,  the  operation  may  be  considered  finished. 
Turn  out  the  lights  under  the  tube  containing  the  boat,  remove 
the  stopper,  and  draw  out  the  boat,  which  now  contains  the 
carbon,  the  slag,  and  the  greater  part  of  the  manganese  (as 
Residue  in  Mnd2)  which  were  contained  in  the  iron  or  steel.  This  residue 

boat  avail- 
able for       may  be  used  for  the  determination  of  the  carbon   or  the  slag, 

donofc  as  will  be  shown  farther  on.  If  another  determination  is  to  be 
>ag'  made,  another  tube  may  be  substituted  for  the  one  which  con- 
tained the  boat,  and  the  analysis  carried  out  in  the  manner 
described  above.  If  not,  put  out  all  the  lights,  close  the 
stopcock,  and  withdraw  the  combustion-tube  with  the  water- 
tubes.  Remove  the  stoppers  from  the  latter,  and  pour  the  con- 
tents of  these  tubes  into  a  platinum  dish  containing  a  small 
amount  of  an  aqueous  solution  of  sulphurous  acid,  to  prevent 
the  chlorine  in  the  solutions  from  acting  on  the  platinum. 
Rinse  the  tubes  into  the  dish,  and  if  any  silica  has  separated 
out  and  adheres  to  the  water-tubes  or  to  the  end  of  the  com- 
bustion-tube, loosen  it  with  a  "  policeman"  and  wash  it  into  the 
dish.  Add  5  c.c.  strong  H2SO4,  evaporate  to  dryness,  and  heat 
until  fumes  of  SO3  are  given  off.  Allow  the  dish  to  cool,  add 
100  c.c.  cold  water,  and  filter  off  on  a  small  ashless  filter  any 
SiO2,  which  burn  and  weigh  as  such.  Calculate  to  Si.  The 
Separation  filtrate  from  the  SiO2  will  contain  any  TiO2  which  may  have 

from  TiO2. 

been    in   the   metal  and   which    can   be  'determined,    as  will   be 
shown    farther    on.      Silicon    and    titanium    are    volatilized    as 


RAPID   METHOD   FOR   SILICON. 

chlorides,  SiCl4  and  TiCl4,  under  the  conditions  shown  above, 
and  decomposed  by  water  thus:  SiCl4  +  2H2O  =  4HC1  +  SiO2 
and  TiCl4  +  2H2O  =  4HC1  +  TiO2. 

tion  by 
H,0. 

Rapid   Method   for    Determination   of   Silicon.      (S.   Alfred 

Ford.*) 

At  the  Edgar  Thomson   Steel-Works   the  molten    pig-metal 
is   taken  directly  from  the  furnaces  to  the  converters,  and  it  is 
generally  necessary  to   determine  the  amount  of  silicon  in  the 
pig-iron  as  a  guide  in  blowing  the  metal.     To  get  the  sample  Method  of 
for  analysis,  a  small  ladle  is  dipped  into  the  iron  as  it  runs  from     ^fe 
the  furnace,  and  a  small  quantity  of  molten  iron  is  taken.     The 
ladle  is  then  held  about  three  feet  above  a  bucket  of  water,  and 
the  molten  metal  drooped  into  the  water,  at  the  same  time  giving 

the  ladle  a  circular  motion  over  the  bucket.     This  will  cause  the  Appearance 

of  shot  de- 
iron  to  form  in   globules,  more  or  less  round  according  to  the     pending 

amount  of  silicon  contained  in  the  iron.  Thus,  with  iron  which  °°  si"™ 
contains  2  per  cent,  of  silicon  or  more,  the  globules  will  be 
almost  perfectly  round,  concave  on  the  upper  surface,  and  gen- 
erally from  j{  inch  (6  mm.)  to  ^  inch  (9  mm.)  in  diameter; 
while  if  the  iron  be  low  in  silicon,  the  shot  or  drops  will  be 
very  small,  flat,  and  irregular  in  shape,  and  if  the  iron  be  very 
low  in  silicon,  as  is  the  case  with  spiegel  and  ferromanganese, 
the  shot  will  be  elongated  and  have  tails  sometimes  *^  inch 
(6  mm.)  in  length.  In  fact,  a  close  observer  can  soon  judge  very 
closely  as  to  the  amount  of  silicon  from  the  condition  of  these 
shot  or  drops.  The  next  step  in  the  process  is  to  take  the  shot 
from  the  bucket  and  place  them  for  a  minute  in  the  ladle  which 
has  been  used  to  dip  up  the  molten  iron.  The  ladle,  being  hot, 
will  dry  the  shot  almost  instantly.  The  shot  are  then  placed  Pulverizing 
in  a  large  steel  mortar  (Fig.  7,  page  17)  and  crushed.  The  ple. 
crushed  shot  are  then  sifted  with  a  fine  sieve,  and  .5  gramme 

*  Prepared  by  Mr.  Ford  for  this  volume. 


78  ANAL  YSIS   OF  IRON  AND   STEEL. 

Determina-    of  the  fine  siftings  are  placed  in  a  platinum  evaporating-dish,  10 

tion  of  the 

Si.  c.c.  HC1,  1.2  sp.  gr.,  are  then  added,  and  the  dish  covered  with 

a  watch-glass.  The  dish  is  then  placed  over  a  light,  and  the  iron 
dissolved ;  as  soon  as  solution  takes  place,  which  requires  about 
one  minute,  as  the  particles  of  iron  are  so  small,  the  watch- 
glass  is  removed  and  the  solution  evaporated  to  dryness  as 
rapidly  as  possible  over  a  naked  light ;  as  soon  as  dry,  not  even 
waiting  for  the  dish  to  cool,  dilute  HC1  is  dropped  on  the 
chloride  of  iron,  and  as  soon  as  all  the  sesquioxide  of  iron 
(which  may  have  been  formed  by  the  decomposition  of  the  chlo- 
ride) is  dissolved,  water  is  added.  The  contents  of  the  dish 
are  then  poured  on  a  filter,  to  which  is  attached  a  pump,  filtered, 
and  washed.  The  filter  and  its  contents  are  then  placed  in  a 

Burning  c  weighed  platinum  crucible,  placed  over  a  blast-lamp ;  as  soon 
of  o.  as  the  filter-paper  is  burned  off,  the  crucible  is  turned  on  its 
side,  the  lid  removed,  and  a  small  jet  of  oxygen  is  driven  very 
gently  into  the  crucible.  As  soon  as  what  little  carbon  there 
is  in  the  precipitate  is  burned  off,  the  crucible  is  cooled  and 
weighed,  and  the  amount  of  silicon  calculated  from  the  weight 
of  the  silica  in  the  crucible. 

Time  re-  By  this  method  the  amount  of  silicon  in  a  pig-iron  can  be 

quired  for 

determi-      determined   in    twelve   minutes  from  the  time   the    ladle  is    put 

nation 

Of  si.         into  the  molten  iron,  and  it  gives  results  close  enough  for  prac- 
tical purposes. 


DETERMINATION    OF   SLAG   AND   OXIDES. 

Presence  of  A  certain  amount  of  slag  and  oxide  of  iron  is  always  present 

and  steel,  in  puddled  iron  as  a  mechanical  admixture.  It  is  also  found, 
as  a  general  thing,  in  basic  steel,  and  the  presence  of  slag  in 
steel  made  by  the  acid  process,  as  well  as  in  pig-iron,  is  not 
unusual.  The  easiest  method  for  the  determination  of  these 
substances  is  by  solution  in  iodine,  as  suggested  by  Eggertz. 


DETERMINATION  OF  SLAG  AND    OXIDES. 


By  Solution  in  Iodine. 

Weigh  5  grammes  of  borings  free  from  lumps  into  a  No.  2  Details  of 
Griffin's  beaker.  Stand  the  beaker,  carefully  covered  with  a  method, 
watch-glass,  in  a  dish  filled  with  scraped  ice  or  snow,  so  that  the 
bottom  and  sides  of  the  beaker  half-way  up  shall  be  in  contact 
with  it.  Pour  over  the  iron  in  the  beaker  25  c.c.  of  ice-cold 
boiled  water,  and  stir  until  all  the  air  in  the  borings  has  escaped. 
Add  gradually  28  or  30  grammes  of  resublimed  iodine,*  stirring 
occasionally,  until  all  the  iodine  has  dissolved.  Keep  the  beaker 
constantly  surrounded  by  ice,  and  add  the  iodine  slowly  enough 
to  prevent  any  rise  in  the  temperature  of  the  solution.  Stir  the 
solution  frequently  until  the  iron  is  perfectly  dissolved,  which 
will  take  several  hours;  then  add  100  c.c.  cold  boiled  water, 
allow  the  insoluble  matter  to  settle,  and  decant  the  supernatant 
fluid  on  a  small  ashless  filter.  Wash  the  insoluble  matter  several 
times,  by  decantation,  with  cold  water,  then  add  to  it  a  little  insuring 

total  solu- 

water,  with  a  few  drops  of  HC1,  and  observe  whether  any  hydro-  tionofFe. 
gen  is  disengaged.  If  none  can  be  perceived,  the  metallic  iron 
may  be  considered  entirely  dissolved ;  but  if  gas  is  given  off, 
the  opposite  is  the  case.  In  either  event,  quickly  decant  the 
acidulated  water  on  the  filter,  and  if  any  metallic  iron  remains, 
add  a  very  little  water  and  some  iodine  to  dissolve  the  iron 
entirely.  Then  transfer  the  insoluble  matter,  consisting  of 
graphite,  carbonaceous  matter,  slag,  oxide  of  iron,  and  some  Separation 
silica,  to  the  filter,  wash  the  filter  once  with  very  dilute  HC1 
(i  acid  to  20  water),  and  finally  with  cold  water,  until  the  filtrate 
is  free  from  iron.  Unfold  the  filter,  and  with  a  fine  jet  wash 
the  insoluble  matter  off  into  a  small  platinum  or  silver  dish. 
Evaporate  almost  to  dryness,  add  50  c.c.  solution  of  caustic 
potassa,  sp.  gr.  i.i,  and  boil  five  or  ten  minutes.  Decant  the 
liquid  on  a  very  small  ashless  filter,  repeat  the  boiling  with 

*  Page  41. 


3O  ANALYSIS   OF  IRON  AND  STEEL. 

fresh  caustic  potassa,  transfer  the  insoluble  matter  to  the  filter, 
and  wash  well  with  hot  water.  Wash  once  with  dilute  HC1 
(i  acid  to  20  water),  and  finally  with  hot  water,  until  the  filtrate 
gives  no  precipitate  with  a  solution  of  nitrate  of  silver.  Dry, 
ignite,  and  weigh  as  Slag  and  Oxide  of  Iron. 

Instead  of  using  iodine  directly  for  the  solution  of  the  iron, 
Use  of  iodine  a  solution  of  iodine  in  iodide  of  iron,  as  suggested  by  Eggertz,* 

in  iodide  of 

iron  as  a  may  be  used  to  great  advantage,  as  it  affords  a  ready  method 
for  getting  rid  of  the  impurities  usually  present  in  resublimed 
iodine.  Treat  5  grammes  of  iron  (as  free  as  possible  from 
silicon)  with  25  grammes  of  iodine,  and,  when  the  solution  is 
complete,  add  30  grammes  more  of  iodine,  which  will  dissolve 
in  the  iodide  of  iron  in  a  few  minutes.  Dilute  to  50  c.c.  with 
cold  boiled  water  and  filter  through  a  washed  filter.  Add  the 
filtrate  at  once  to  5  grammes  of  the  weighed  sample,  and,  after 
solution  is  complete,  proceed  as  directed  above. 

By  Volatilization  in  a  Current  of  Chlorine  Gas. 

Proceed  exactly  as  in  the  method  for  the  determination  of 

silicon  (pages  74  et  seq.}  until  the  boat  is  withdrawn  from  the 

washing  out  combustion-tube.     Wash  the  contents  of  the  boat  into  a  small 

chlorides,    beaker  with  a  jet  of  cold  water,  and  filter  on  a  small   ashless 

filter.     The  water  dissolves  any  soluble  metallic  chlorides,  MnCl2, 

CaCl2,  etc.,  which  are  not  volatile  at  a  low  red   heat,  and  the 

insoluble  matter  in  the  filter  consists  of  slag  and  carbon.     Burn 

off  the  carbon  and  weigh  the  residue  as  Slag  and  Oxides.     Or, 

Using  coun-    if  the  carbon   has  been   determined  by  another  operation,  filter 

terpoised 

filters.  the  carbon  and  slag  on  a  counterpoised  filter  j  or  on  a  Goocn 
crucible,  dry  at  100°  C.,  and  weigh  as  Carbon,  Slag,  and  Oxides; 
by  subtracting  the  weight  of  the  carbon  the  difference  is  Slag 
and  Oxides. 


*  Jern-Kontorets  Annaler,  1 88 1,  p.  301,  and  Chem.  News,  xliv.  173. 
f  See  page  27. 


DETERMINATION  OF  PHOSPHORUS.     OF  QT 

™ 


DETERMINATION  OF  PHOSPHORUS. 

For  the  determination  of  phosphorus  in  iron  and  steel  but 
two  methods  are  in  general  use,  either  of  which,  properly 
carried  out,  will  give  extremely  accurate  results.  Some  chemists 
prefer  one  method,  some  the  other,  while  a  combination  of  the 
two  is  sometimes  used.  The  two  general  methods  are  known 
respectively  as  the  Acetate  Method  and  the  Molybdate  Method.  Methods  in 
There  are  innumerable  variations  in  the  details,  especially  of 
the  latter  method,  but  any  departure  from  what  might  be 
termed  the  standard  instructions  should  never  be  attempted  by 
any  but  a  very  experienced  analyst. 

The  Acetate  Method. 

The  essential  parts  of  this  method  were  suggested  by  Fre- 
senius,*  the  changes  and  improvements  in  details  being  the 
work  of  many  chemists.t 

Treat  5  grammes  of  drillings  in  a  No.  4  Griffin's  beaker  with   Detailsof 

the  acetate 

80  c.c.  HNO3  (1.2  sp.  gr.),  and,  when  violent  action  has  ceased,     method. 

add  10  c.c.  strong  NCI.     Evaporate  the  solution  to  dryness  in  the 

air-bath,  replace  the  cover,  and  heat  until  the  nitrate  of  iron  is 

nearly  all  decomposed.      Cool,  add  30  c.c.  HC1,  heat  gradually 

until  the  oxide  of  iron  is  dissolved,  and  evaporate  to  dryness  again 

in  the  air-bath.    Cool,  dissolve  in  30  c.c.  HC1,  dilute,  and,  in  steels 

or  puddled  iron,  when  silicon  is  to  be  determined,  filter,  and  treat  When  si  is 

to  be  de- 

the  insoluble  matter  as  directed  for  the  determination  of  Si,  page  72. 

In  the  case  of  pig-irons  which  may  contain  titanium,  filter, 
and  keep  the  residue  of  graphite,  silica,  etc.,  for  treatment,  as 
directed  farther  on,  "  when  titanium  is  present." 

In  the  case  of  steels,  when  silicon  is  not  to  be  determined  when  si  is 

not  to  be 

in  this  portion,  the  solution  need  not  be  filtered  at  all,  but  may     deter- 
be  diluted  at  once  to  about  250  c.c. 

*  Jour,  fiir  Pr.  Ch.,  xlv.  258. 

f  Tenth  Census  of  the  U.  S.,  vol.  xv.     "  Iron  Ores  of  the  U.  S.,"  p.  523. 

6 


IS 

present. 


32  ANALYSIS   OF  IRON  AND   STEEL. 

In  any  case,  heat  the  filtered  or  unfiltered  HC1  solution 
nearly  to  boiling,  remove  the  beaker  from  the  light,  and  add 
gradually  from  a  small  beaker  a  mixture  of  10  c.c.  NH4HSO3* 
and  20  c.c.  NH4HO,  stirring  constantly.  The  precipitate,  which 
forms  at  first,  redissolves,  and  when  all  but  about  2  or  3  c.c. 
of  the  NH4HSO3  solution  has  been  added,  replace  the  beaker 
Deoxidiz-  over  the  light.  If  at  any  time  while  adding  the  NH4HSO3 
solution,  solution  the  precipitate  formed  will  not  redissolve  even  after 
vigorous  stirring,  add  a  few  drops  of  HC1;  and,  when  the  solu- 
tion clears,  continue  the  addition,  very  slowly,  of  the  NH4HSO3. 
After  replacing  the  beaker  on  the  light,  add  to  the  solution 
(which  should  smell  quite  strongly  of  SO2)  NH4HO,  drop  by 
drop,  until  the  solution  is  quite  decolorized,  and  until  finally  a 
slight  greenish  precipitate  remains  undissolved  even  after  vig- 
orous stirring.  Now  add  the  remaining  2  or  3  c.c.  of  the 
NH4HSO3  solution,  which  should  throw  down  a  white  precipi- 
tate, which  usually  redissolves,  leaving  the  solution  quite  clear 
and  almost  perfectly  decolorized.  Should  any  precipitate  remain 
undissolved,  however,  add  HC1,  drop  by  drop,  until  the  solution 
clears,  when  it  should  smell  perceptibly  of  SO2.  If  the  reagents 
are  used  in  exactly  the  proportions  indicated,  the  reactions  will 
take  place  as  described,  and  the  operations  will  be  readily  and 
quickly  carried  out.  If  the  solution  of  NH4HSO3  is  weaker 
than  it  should  be,  of  course  the  ferric  chloride  will  not  be 
reduced,  and  the  solution,  at  the  end  of  the  operation  described 
above,  will  not  be  decolorized  and  will  not  smell  of  SO2.  In 
this  case  add  more  of  the  NH4HSO3  (without  the  addition  of 
NH4HO)  until  the  solution  smells  strongly  of  SO2,  then  add 
NH4HO  until  the  slight  permanent  precipitate  appears,  and 
redissolve  it  in  as  few  drops  of  HC1  as  possible.  The  solution 
being  now  very  nearly  neutral,  the  iron  in  the  ferrous  condition, 
and  an  excess  of  SO2  being  present,  add  to  the  solution  5  c.c. 

*  See  page  44. 


DETERMINATION  OF  PHOSPHORUS.  3^ 

of  HC1  to  make  it  decidedly  acid  and  to  insure  the  complete 
decomposition  of  any  excess  of  the  NH4HSO3  which  may  be 
present.      Boil    the    solution,*   while    a    stream    of    CO2    passes  Boiling  off 
through  it,   until  every  trace  of  SO2  is   expelled,  then   pass   a     ^^ 
current  of  H2S  through  it  for  about  fifteen  minutes  to  precipi- 

FIG.  50. 


tate  any  arsenic  which  may  be  present,  and  finally  allow  the 
solution  to  stand  in  a  warm  place  until  the  smell  of  H2S  has 
disappeared,  or,  better,  pass  a  current  of  CO2  through  the 

*  By  passing  a  current  of  CO2  through  the  boiling  solution  the  SO2  is  soon  ex- 
pelled, and  the  operation  requires  no  watching. 


ing  the  As. 


84 


ANALYSIS   OF  IRON-  AND   STEEL. 


solution,  which  will  expel  the  H2S  in  a  few  minutes.  The 
arrangement,  Fig.  50,  is  convenient  for  this  purpose.  Filter 
from  any  As2S3,  CuS,  S,  etc.,  into  a  No.  5  beaker,  wash  with 
cold  water,  and  to  the  filtrate  add  a  few  drops  of  bromine-water, 
and  cool  it  by  placing  the  beaker  in  cold  water.  To  the  cold 
solution  add  NH4HO  from  a  small  beaker  very  slowly,  and 
finally  drop  by  drop,  with  constant  stirring.  The  green  pre- 
cipitate  of  ferrous  hydrate  which  forms  at  first  is  dissolved  by 
stirring,  leaving  the  solution  perfectly  clear,  but  subsequently, 
drate.  although  the  green  precipitate  dissolves,  a  whitish  one  remains, 
and  the  next  drop  of  NH4HO  increases  the  whitish  precipitate 
or  gives  it  a  reddish  tint,  and  finally  the  greenish  precipitate 
remains  undissolved  even  after  vigorous  stirring,  and  another 
drop  of  NH4HO  makes  the  whole  precipitate  appear  green. 
If  before  this  occurs  the  precipitate  does  not  appear  decidedly 
red  in  color,  dissolve  the  green  precipitate  by  a  drop  or  two 
of  HC1,  and  add  a  little  bromine-water  (i  or  2  c.c.),  then  add 
NH4HO  as  before,  and  repeat  this  until  the  reddish  precipitate 
is  obtained,  and  then  the  green  coloration  as  described  above. 
Dissolve  this  green  precipitate  in  a  very  few  drops  of  acetic  acid 
(sp.  gr.  1 .04),  when  the  precipitate  remaining  will  be  quite  red  in 
color,  then  add  about  I  c.c.  of  acetic  acid,  and  dilute  the  solu- 
tion with  boiling  water,  so  that  the  beaker  may  be  about  four- 
Filtering  and  fifths  full.  Heat  to  boiling,  and  when  the  solution  has  boiled 
riieVr"8  one  minute,  lower  the  light,  filter  as  rapidly  as  possible  through 
a  5^-inch  (i4O-mm.)  filter,  and  wash  once  with  hot  water. 
The  filtrate  should  run  through  clear,  but  in  a  few  minutes  it 
will  appear  cloudy  by  the  precipitation  of  the  ferric  oxide,  which 
has  been  formed  by  the  exposure  of  the  filtered  solution  to  the 
Precautions,  air.  The  points  to  be  observed  are  the  red  color  of  the  precipi- 
tate and  the  clearness  of  the  solution  when  it  first  runs  through. 
Ferric  phosphate  being  white,  the  red  color  of  the  precipitate 
shows  that  enough  ferric  salt  was  present  in  the  solution  to 
form  ferric  phosphate  with  all  the  phosphoric  acid,  and  enough 


DETERMINATION  OF  PHOSPHORUS.  35 

more  to  color  the  ferric  phosphate  red  with  the  excess  of  ferric 
oxide. 

When  the  precipitate  has  drained  quite  dry,  pour  about  15  c.c. 
of  HC1  into  the  beaker  in  which  the  precipitation  was  made, 
warm  it  slightly  so  that  the  acid  may  condense  on  the  sides  and  Solution  of 

the  prccip" 

dissolve  any  adhering  oxide,  wash  off  the  cover  into  the  beaker,     Hate. 
add  about  10  c.c.  of  bromine-water,  pour  this  on  the  filter  con- 
taining the  precipitate,  allowing  it  to  run  around  the  edge  of  the 
filter,  and   let   the   solution    run    into  a  No.    I    Griffin's   beaker. 
Wash  out  the  beaker  once  or  twice,  and  then  wash  the  filter 
well  with  hot  water.     If  the  acid  in  the  beaker  is  not  sufficient 
to  dissolve  the  precipitate  completely,  drop  a  little  strong  acid 
around  the  edge  of  the  filter  before  washing  it  with  hot  water. 
The  scaly  film  of  difficultly  soluble  oxide  which  sometimes  forms  cause  of 
on  boiling  the  acetate  precipitate  is  caused  by  the  presence  of     cuitiy  sol. 
too  much  acetate  of  ammonium,  but  when  the  instructions  given 
above   are   carefully   carried   out   it   never   appears.      Evaporate 
the  solution  in  the  small  beaker  nearly  to  dryness  to  get  rid 
of  the  excess   of  HC1,  add  to  it  a  filtered  solution  of  5   or  10 
grammes  of  citric  acid  (according  to  the  size  of  the  precipitate 
of  Fe2O3,   etc.)   dissolved  in    10  to  20  c.c.  of  water,  then   5   to 
10  c.c.  of  magnesia-mixture  and  enough   NH4HO  to  make  the 
solution  faintly  alkaline.     Stand  the  beaker  in  cold  water,  and 
when  the  solution  is  perfectly  cold,  add  to  it  one-half  its  volume 
of  strong   NH4HO   and   stir  it  well.     When  the  precipitate  of   Predpita- 
Mg2(NH4)2P2O8  has  begun  to  form,  stop  stirring,  and  allow  it  to     th°Mg, 
stand  in  cold  water  for  ten  or  fifteen  minutes,  then  stir  vigorously     ^4)s 
several  times  at  intervals  of  a  few  minutes,  and  allow  it  to  stand 
overnight.      Filter   on  a   small   ashless    filter,  and  wash  with  a 
mixture  of  2  parts  of  water  and    I   part  of  NH4HO  containing 
2.5  grammes  of  NH4NO3  to   100  c.c. 

Dry  the  filter  and  precipitate,  and  ignite  them  at  a  very  low  Filtering 

and   burn- 

temperature  at  first  so  as  to  carbonize  the  filter  without  decom-     ingthe 
posing  the  precipitate,  which    may  then  be    readily  broken   up     tate. 


86 


ANALYSIS   OF  IRON  AND   STEEL. 


Treatment 
soluble 


Treatment 


with  a  platinum  wire.  Raise  the  heat  gradually,  and  finally 
ignite  at  the  highest  temperature  of  the  Bunsen  burner.  When 
the  precipitate  is  perfectly  white,  cool  and  weigh.  Then  fill 
the  crucible  half  full  of  hot  water,  add  from  5  to  20  drops  of 
HC1,  and  heat  until  the  precipitate  has  dissolved.  Filter  off  on 
another  small,  ashless  filter  any  SiO2  or  Fe2O3  that  may  remain, 
ignite,  and  weigh.  The  difference  between  the  two  weights  is 
the  weight  of  Mg2P2O7,  which,  multiplied  by  0.27836,  gives  the 
weight  of  P. 

When  Titanium  is  Present. 

When  a  solution  of  ferric  chloride  containing  TiO2  and  P2O5 
is  evaporated  to  dryness,  a  compound  of  TiO2,P2O5  and  Fe2O3  is 
formed,  completely  insoluble  in  dilute  HCL* 

Iron  ores  and  pig-irons  containing  TiO2  require,  therefore,  a 
somewhat  different  method  of  treatment  from  that  given  above. 

Dry  and  ignite  the  residue  of  graphite,  silica,  etc.,  from  the 
solution  of  the  pig-iron,  so  as  to  burn  off  all  the  carbon.  Moisten 
this  residue  with  cold  water,  add  5  to  10  drops  of  H2SO4  and 
enough  HF1  to  dissolve  the  silica,  and  evaporate  until  fumes 
of  SO3  are  given  off.  While  this  is  going  on,  proceed  with  the 
deoxidation  of  the  filtrate  as  described  above,  but  when  the  SO2 
has  been  driven  off  do  not  pass  H2S  through  the  solution,  but 
cool  it,  and  proceed  with  the  acetate  precipitation.  Instead  of 
dissolving  the  precipitate,  after  washing  it  as  described  above,  dry 
the  filter  and  precipitate  in  the  funnel,  being  careful  not  to  heat 
it  so  as  to  scorch  the  filter.  Clean  out  any  of  the  precipitate 
which  may  have  adhered  to  the  sides  of  the  beaker  in  which  the 
precipitation  was  made,  by  wiping  it  with  filter-paper,  and  dry 
this  paper  with  the  filter  and  precipitate. 

When  the  precipitate  is  quite  dry,  transfer  it  to  a  small  por- 
celain mortar.  The  precipitate  may  be  readily  detached  from 


*  Published  in  Report  on  Methods  employed  in  the  Analysis  of  the  "  Iron  Ores," 
Tenth  Census  U.S.,  vol.  xv.  p.  512.     I  first  noted  this  fact  in  1878. 


DETERMINATION  OF  PHOSPHORUS.  g* 

the  filter  by  rubbing  the  sides  of  the  latter  together  over  a  large 
piece  of  white,  glazed  paper,  so  that  any  little  particles  that  fall 
out  may  be  seen.  Roll  up  the  filter  with  the  bits  of  paper  which 
were  used  to  wipe  out  the  beaker,  wrap  a  piece  of  platinum 
wire  around  it,  burn  it  on  the  lid  of  the  crucible  in  which  the 
graphitic  residue  was  treated,  and  transfer  the  ash  to  the  mortar. 
Grind  the  precipitate  and  ash  with  3  to  5  grammes  of  Na2CO3  Fusion  of  the 

precipi- 

and  a  little  NaNO3,  and  transfer  it  to  the  crucible  containing  tate. 
the  residue  which  was  treated  by  HF1  and  H2SO4.  Clean  the 
mortar  and  pestle  by  grinding  a  little  more  Na2CO3,  and  add 
this  to  the  other  portion  in  the  crucible.  Fuse  the  whole  for 
half  an  hour  or  more,  cool,  dissolve  the  fused  mass  in  hot  water, 
filter  from  the  insoluble  Fe2O3,  etc.,*  acidulate  the  filtrate  with 
HC1,  add  a  few  drops  of  NH4HSO3,  boil  off  all  smell  of  SO2, 
and  pass  H2S  through  the  hot  solution  to  precipitate  any  arsenic 
that  may  be  present.  Pass  a  current  of  CO2  through  the  solu-  Precipita- 
tion to  expel  the  excess  of  H2S,  filter  off  the  As2S3,  and  to  the  AS. 
filtrate  add  a  sufficient  amount  of  Fe2Cl6  solution  to  combine 
with  all  the  P2O5  as  Fe2(PO4)2  and  leave  a  slight  excess.  Add 
a  slight  excess  of  NH4HO,  which  should  throw  down  a  red 
precipitate,  while-  the  solution  is  alkaline  to  test-paper ;  then  add 
acetic  acid  to  slightly  acid  reaction,  boil,  and  filter  off  the 
Fe2(PO4)2  and  Fe2O3,  and  wash  with  hot  water.  Dissolve  the 
precipitate  in  HC1,  allow  the  solution  to  run  into  a  small  beaker,  Predpita- 

. ,  t  .  tion  of  the 

evaporate  until  the  solution  is  syrupy,  add  citric  acid  and  mag-     Mg2 

nesia-mixture,  and   precipitate   the    Mg2(NH4)2P2O8  as   described     pj^ 

above.     Unless  the  amount  of  phosphorus  is  very  small,  a  second 

fusion  of  the  insoluble  residue  of  Fe2O3,  etc.,  is  necessary.     The  Necessityfor 

two  filtrates  can  then  be  added  together,  acidulated  with  HC1, 

and  the  remainder  of  the  process  carried  out  as  directed  above. 

To  avoid  the  fusion  of  the  acetate  precipitate  with  Na2CO3,  which 


*  This  Fe2O3,  etc.,  contains  all  the  titanium  that  was  in  the  pig-iron  as  titanate  of 
soda,  and  must  be  kept  for  the  estimation  of  that  element  when  it  is  to  be  determined. 


88  ANALYSIS   OF  IRON  AND   STEEL. 

is  always  troublesome,  the  method  for  the  determination  of 
phosphorus  may  be  modified  (in  many  cases  with  advantage, 
and  generally  when  titanium  is  not  to  be  estimated)  as  follows  : 
After  filtering  off  the  insoluble  matter,  graphite,  silica,  etc.,  ignite 
it,  burn  off  the  graphite,  and  treat  the  residue  with  HF1  and 
H2SO4,  evaporate  down  until  the  excess  of  H2SO4  is  driven  off, 
and  fuse  with  Na2CO3.  Treat  the  fused  mass  with  water,  and 
filter.  Acidulate  the  filtrate  with  HC1,  and  add  it  to  the  main 
Method  to  solution,  which  has  been  deoxidized  in  the  mean  time  with  bisul- 
phite  of  ammonium.  Expel  the  last  traces  of  SO2  from  the 
umted  filtrates  by  boiling  and  passing  a  current  of  CO2  through 


acetate       £he  solution,  as  previously  directed.     If  the  solution  remains  clear, 

precipi- 

tate-          pass   H2S   through    it,   and   filter   off  the   precipitated    sulphides. 

Cool  the  solution,  and  make  the  acetate  precipitation  as  directed 

Tendency  of  on  page   84.     The   only  danger  to  be   apprehended   now  is   the 

TiO2  to 

separate  tendency  of  titanic  acid  to  separate  out  and  carry  phosphoric 
acid  with  it  when  in  the  evaporation  of  the  HC1  solution  of  the 
acetate  precipitate  the  liquid  becomes  concentrated.  To  avoid 
this,  the  evaporation  must  be  watched  very  carefully,  and  citric 
acid  added  as  soon  as  the  titanic  acid  begins  to  separate.  Then, 
if  the  separation  has  not  proceeded  too  far,  the  phosphoric  acid 
may  be  precipitated  in  the  usual  way.  If,  however,  the  separation 
of  titanic  acid  is  not  checked  in  time,  proceed  with  the  evapo- 
ration as  directed  on  page  85,  add  5  c.c.  strong  HC1,  and  warm 
gently.  The  solution  will  nearly  always  clear,  but  if  it  does 
not,  then  add  citric  acid  and  a  slight  excess  of  ammonia,  and 
filter.  Stand  the  filtrate  aside,  burn  off  and  fuse  the  precipitate 
with  Na2CO3,  dissolve  in.  water,  filter,  acidulate  the  filtrate  with 
HC1,  add  a  little  Fe2Cl6  solution,  a  slight  excess  of  ammonia, 
and  acidulate  with  acetic  acid.  Boil,  filter  off  the  precipitate 
of  phosphate  and  oxide  of  iron,  dissolve  in  a  little  HC1,  allow 
the  solution  to  run  into  a  small  beaker,  evaporate  down,  and  add 
it  to  the  ammoniacal  filtrate  from  the  separated  titanic  acid 
obtained  above.  Add  excess  of  magnesia-mixture,  and  precip- 


DETERMINATION  OF  PHOSPHORUS. 


89 


itate  the  phosphoric  acid  in  the  usual  way.     When  the  solution  other 

sources  of 

becomes  cloudy  after  deoxidation  with  NH4HSO3,  and  remains  error. 
so  after  acidulating  with  HC1,  proceed  as  directed  above,  but 
dry,  and  ignite  the  filter  containing  the  precipitate  by  H2S  and 
that  on  which  the  acetate  precipitate  was  filtered,  fuse  with 
Na2CO3,  treat  with  water,  filter,  acidulate  with  HC1,  pass  H2S 
through  the  solution,  filter,  add  a  little  Fe2Cl6  solution,  and  pre- 
cipitate by  ammonia  and  acetic  acid.  Add  the  solution  of  this 
precipitate,  after  filtering  it  off,  to  the  solution  of  the  main 
acetate  precipitate,  and  proceed  as  before. 

Instead  of  adding  citric   acid  and   magnesia-mixture  to   the  Removing 
solution   of  the    acetate   precipitate,    Fresenius,*  and    afterwards     Fes  before 


Spiller,t   advised   the   method   of  adding  citric  acid,   excess   of 
ammonia,  and  sulphide  of  ammonium,  filtering  off  the  precipi- 
tated  sulphide  of   iron,   and,   after    evaporating    to    small   bulk, 
adding  magnesia-mixture  and  ammonia.     When  the  bulk  of  the 
iron  precipitate  is  not  too   great,  this  is  quite   unnecessary,  for  Shown  to  be 
many  determinations   have  shown  that  with  an  excess  of  mag-     sary- 
nesia-mixture,   ammonium    magnesium   phosphate   is    absolutely 
insoluble  in  both  citrate  of  iron  and  ammonium  and  citrate  of 
aluminium  and  ammonium. 

The   precipitate  is   also   insoluble  in  ammonia-  water  (i   part 
of  NH4HO  to  2  parts  of  water). 

The  Molybdate  Method. 

Svanberg  and  StruveJ  first  discovered  the  reaction  on  which 
this  method  is  based,  and  Sonnenschein  §  first  used  it  quantita- 
tively. Weigh  5  grammes  of  drillings  into  a  No.  4  Griffin's 
beaker,  and  add,  with  the  proper  precautions  (page  65),  40  c.c. 
strong  HNO3.  Instead  of  using  HC1  to  hurry  the  solution,  it  solution. 
is  better,  when  the  action  slackens,  to  add  water  very  cautiously 

*  Jour,  fur  Pr.  Chem.,  xlv.  258.  f  Jour.  Chem.  Soc.  (2),  iv.  148. 

J  Jour,  fur  Pr.  Chem.  xliv.  291.  g  Jour,  fur  Pr.  Chem.,  liii.  339. 


9o 


ANALYSIS   OF  IRON  AND   STEEL. 


from  time  to  time  until  the  metal  is  completely  dissolved.  Evapo- 
rate to  dryness  in  the  air-bath,  replace  the  cover,  and  heat  for 
one  hour  at  a  temperature  of  about  200°  C.  in  order  to  decom- 

Destroying     pose   all   the    carbonaceous   matter,*   otherwise  the  precipitation 

bonaceous   of  the  phospho-molybdate  will  be  incomplete.     Allow  the  beaker 

to  cool,  dissolve  the  precipitate  in  30  c.c.  HC1,  evaporate  to  dry- 

ness  to  render  the   silica   insoluble,  redissolve   in    30  c.c.   HC1, 

Removal  of  and  evaporate  carefully  until  the  excess  of  HC1  is  driven  off, 
shaking  the  beaker  from  time  to  time  to  prevent  the  forma- 
tion of  a  crust  of  dry  chloride  of  iron.  Cool  the  beaker,  and 
dilute  the  solution  with  twice  its  volume  of  cold  water.  Filter 
on  a  small,  washed  German  filter,  3-inch  (7  5  -mm.),  or  on  the 
Gooch  crucible.  In  the  latter  case  the  precipitation  of  the 
phospho-molybdate  may  be  made  in  the  small  flask  into  which 
the  solution  is  filtered.  The  washing  should  be  done  with  cold 
water  after  dropping  a  little  dilute  HC1  around  the  edge  of  the 

Volume  of  filter.  The  filtrate  and  washing  should  not  exceed  50  or  60  c.c. 
aon.  in  volume.  Add  to  the  solution  50  to  100  c.c.  molybdate  solu- 


tion,f  heat   it  to  40°  C.   in  a  water-bath  carefully  kept  at   this 

ture  of  the 

solution,  temperature,  and  allow  it  to  stand  in  the  bath  for  about  four 
hours.  Filter  on  a  small,  washed  filter,  and  wash  thoroughly 
with  dilute  molybdate  solution  (i  part  of  solution  to  I  part  of 
water)  until  a  drop  of  the  filtrate  gives  no  reaction  for  iron 
with  ferrocyanide  of  potassium.  Stand  the  filtrate  aside  in  a 
warm  place  to  see  whether  any  further  precipitation  of  phospho- 
Soiutionof  molybdate  of  ammonium  takes  place;  if  it  does,  it  must  be 
filtered  off  and  treated  like  the  main  precipitate.  Pour  2  or  3^ 
c-c-  strong  NH4HO  on  the  precipitate,  stir  it  up  with  a  fine  jet 
of  hot  water,  and  allow  the  solution  to  run  into  the  flask  or 
beaker  in  which  the  precipitation  of  phospho-molybdate  was 

*  In  1877  I  discovered  the  necessity  for  destroying  the  carbonaceous  matter,  and 
communicated  the  fact  to  Hunt  and  Peters,  who  mentioned  it  in  the  Metallurgical 
Review,  vol.  ii.  p.  365. 

f  See  page  59. 


DETERMINATION  OF  PHOSPHORUS.  QJ 

made.  When  it  has  all  run  through  the  filter,  replace  the  flask 
or  beaker  by  a  small  beaker  of  a  little  over  100  c.c.  capacity, 
remove  any  phospho-molybdate  that  may  have  adhered  to  the 
sides  of  the  original  flask  or  beaker,  by  means  of  the  ammoni- 
acal  filtrate,  and  then  pour  this  back  on  the  filter  and  allow  it 
to  run  through  into  the  small  beaker.  Wash  out  the  beaker  or 
flask  with  hot  water  and  pour  it  on  the  filter  with  the  addition 
of  a  little  more  NH4HO.  Unless  the  precipitate  of  phospho- 
molybdate  is  very  large,  this  amount  of  NH4HO  should  dis- 
solve it,  and  a  very  little  more  washing  should  be  sufficient. 
If  the  precipitate  is  very  large,  it  may  be  necessary  to  use  more  Volume  of 
NH4HO  and  more  wash-water,  but  under  all  circumstances  the  niacaiso- 
amount  of  NH4HO  and  of  wash-water  should  be  as  small  as  is 
consistent  with  perfect  solution  of  the  precipitate  and  thorough 
washing  of  the  beaker  and  filter.  When  the  precipitate  is 
small,  the  filtrate  and  washings  should  amount  to  about  25  c.c. 
Neutralize  the  solution  with  strong  HC1 ;  if  the  yellow  phospho-  ^ 
molybdate  begins  to  precipitate,  add  NH4HO  until  it  redissolves, 
and  if  there  should  remain  a  flocculent  white  precipitate,  prob- 
ably silica,  after  the  solution  is  quite  alkaline,  filter  it  off. 
Then  to  the  cold  alkaline  liquid  add,  very  slowly,  10  c.c. 
magnesia-mixture,  stirring  constantly,  and  after  the  magnesia- 
mixture  is  all  in,  add  one-third  the  volume  of  the  solution  of  P2°8' 
strong  NH4HO  and  stir  vigorously.  It  is  well  to  stand  the 
beaker  in  cold  water  and  stir  the  solution  several  times  after 
the  precipitate  has  begun  to  crystallize  out.  After  standing 
about  four  hours,  it  may  be  filtered  off  on  a  very  small  ashless 
filter  and  washed  with  dilute  ammonia- water  (i  part  NH4HO  to 
2  parts  water)  containing  2.5  grammes  nitrate  of  ammonium  to 
the  100  c.c.  Dry,  ignite  very  carefully  to  burn  off  the  carbon-  Filtration 
aceous  matter,  and  finally  heat  for  ten  minutes  over  the  blast- 
lamp  to  volatilize  any  molybdic  acid  that  may  have  been 
precipitated  with  the  Mg2(NH4)2P2O8,  cool,  and  weigh.  Fill  the 
crucible  half  full  of  hot  water,  add  5  to  20  drops  HC1,  and 


92 


ANALYSIS   OF  IRON  AND   STEEL. 


date. 


heat  for  a  few  minutes  to  dissolve  the  Mg2P2O7.  Pour  the 
contents  of  the  crucible  on  a  small  ashless  filter,  wash,  ignite, 
and  weigh  the  small  residue  that  may  remain  undissolved.  The 
difference  between  the  two  weights  is  the  weight  of  Mg2P2O7, 
which  contains  27.836  per  cent,  phosphorus. 

Direct  Many    chemists,    following    Eggertz,*    prefer    to    weigh    the 

of  the  yellow  phospho-molybdate  direct  instead  of  dissolving  it  and 
precipitating  as  Mg2(NH4)2P2O8.  In  this  event  take  I  gramme 
of  the  drillings  and  proceed  exactly  as  directed  above,  but  use 
only  about  one-third  the  amount  of  HNO3  and  HC1  for  the 
solution.  Before  adding  the  molybdate  solution,  the  volume  of 
the  filtrate  from  the  silica  should  amount  to  only  about  25  c.c. 
Add  50  c.c.  of  the  molybdate  solution,  allow  it  to  stand  four 
hours  at  a  temperature  of  40°  C.,  and  filter  off  the  precipitated 
phospho-molybdate  on  a  Gooch  crucible;  wash  first  with  dilute 
molybdate  solution,  and  finally  with  water  containing  I  per 
cent,  of  HNO3,  dry  in  an  air-bath  heated  to  120°  C.,  and  weigh 
as  (NH4)3uMoO3PO4  (approximate  formula),  containing  1.63  per 
cent,  of  phosphorus.  In  the  absence  of  a  Gooch  crucible,  use 
counterpoised  filters  f  for  weighing  the  phospho-molybdate.  The 
points  of  special  importance  are : 

First,  the  necessity  for  destroying  all  the  carbonaceous  matter 
by  heating  the  nitric  acid  solution,  after  evaporation,  to  a  suffi- 
ciently high  temperature  to  effect  this  with  certainty. 

Second,  the  avoidance  of  an  excess  of  HC1  in  the  final  solu- 
tion before  precipitating  by  molybdate  solution. 

Third,  when  the  phospho-molybdate  is  weighed  directly,  the 
necessity  for  rendering  the  silica  insoluble. 

Fourth,  the  danger  of  heating  the  solution  above  40°  C. 
after  adding  the  molybdate  solution,  as  arsenic,  when  present, 
precipitates  with  the  phosphorus  if  the  solution  is  heated  to  a 
higher  temperature. 


Precautions 
necessary. 


*  Jour,  fur  Pr.  Chem.,  Ixxix.  496. 


f  See  page  28. 


DETERMINATION  OF  PHOSPHORUS. 


93 


Fifth,  the  danger  of  causing  a  precipitation  of  molybdic  acid 
with  the  phospho-molybdate  by  heating  the  solution  to  a  tem- 
perature approximating  100°  C. 

Some  chemists  prefer  to  drive  off  the  HC1  entirely  by  adding  variations 
HNO3   to    the   hydrochloric    acid    solution,    and    boiling    down     detafli. 
nearly  to  dryness  once  or  twice  before  filtering  off  the  silica. 

Others,  after  filtering  off  the  silica,  add  NH4HO  until  a  slight 
permanent  precipitate  appears,  then  the  molybdate  solution,  which 
is  sufficiently  acid  to  redissolve  the  slight  precipitate  of  ferric 
hydrate,  and  leave  the  solution  quite  clear,  with  the  exception 
of  the  precipitate  of  phospho-molybdate.  Others  supersaturate 
the  hydrochloric  acid  solution  with  NH4HO,  and  redissolve  with 
the  least  possible  amount  of  HNO3  before  adding  the  molyb- 
date solution.  Many  of  these  are  matters  of  personal  preference, 
but  the  safest  plan  for  the  beginner  is  to  follow  the  instructions 
first  given  until  he  has  sufficient  knowledge  and  experience  to 
judge  of  the  value  of  these  variations,  or  to  invent  some  for 
himself. 

The  Combination   Method. 

Riley*  was  the  first  to  suggest  the  precipitation  of  phos-  . 
phorus  as  phospho-molybdate,  preceded  by  a  separation  of  the 
phosphoric  acid  from  the  mass  of  the  ferric  chloride  by  deoxi- 
dation  and  precipitation  by  the  acetate  method.  This  method 
was  worked  out  afterwards  by  A.  Wendel,  of  the  Albany  and 
Rensselaer  Steel  Company,  S.  Peters,  of  the  Burden  Iron  Com- 
pany, and  J.  L.  Smith.f 

Proceed  as  directed  for  the  determination  of  phosphorus  by  Details 

of  the 

the   Acetate  Method,  using    I    gramme   of  borings   and   proper-     method, 
tional   amounts  of  reagents   until    having   dissolved   the   acetate 
precipitate  in    HC1,  evaporate  to    dryness,   redissolve  in   a  very 
little   HNO3,  dilute  to   20  c.c.  with  water,  add  a  slight  excess 
of  NH4HO,  redissolve  the   precipitated   ferric   oxide   in   HNO3, 

*  Jour.  Chem.  Soc.,  1878,  vol.  i.  p.  104.  f  Chem.  News,  xlv.  195. 


94  ANAL  YSIS   OF  IRON  AND   STEEL. 

and  add  30  c.c.  molybdate  solution.  Heat  to  40°  C.  for  an 
hour,  filter,  wash  with  water  containing  I  per  cent,  of  HNO3, 
dry,  and  weigh. 

When  Titanium  is  Present. 

When  phosphorus  is  determined  in  pig-irons  containing  tita- 
nium, burn  off  the  residue  of  carbon,  silica,  etc.,  treat  it  with 
HF1  and  H2SO4,  evaporate,  and  heat  until  the  greater  part  of  the 
H2SO4  is  driven  off.  Fuse  with  2  or  3  grammes  of  carbonate 
of  sodium,  dissolve  in  water,  filter,  acidulate  the  filtrate  with 
HNO3,  add  50  c.c.  molybdate  solution,  and  heat  to  40°  C.  for 
four  hours.  Filter,  wash,  and  add  this  precipitate  to  the  one 
obtained  in  the  filtrate  from  the  carbon,  silica,  etc.  If  any  slight 
insoluble  matter  should  remain  on  the  filter  upon  dissolving  in 
NH4HO  the  phospho-molybdate  obtained  in  the  filtrate  from  the 
carbon,  silica,  etc.,  burn  it,  fuse  it  with  carbonate  of  sodium,  and 
test  it  also  for  phosphorus. 

As  remarked  above,  page  92,  the  formula  given  for  the  dried 
Variable  phospho-molybdate  of  ammonium  is  approximate  only.  The 

composi- 

don  of  the  composition  of  the  salt  seems  to  vary  very  much,  the  percentage 
mo°yb-°~     °f  phosphorus    in    it   being   given   by   various    authorities    from 
1.27  to   1.75.      It  seems  to  depend   upon  various  circumstances, 
such   as  the   presence   or   absence  of  HC1   in    the    solution,  the 
degree  of  acidity,  the  temperature  at  which  the  precipitation  is 
effected,  the  length  of  time  the  solution  stands  before  the  pre- 
cipitate is   filtered   off,  the    size   of  the  precipitate,  the   state   of 
concentration  of  the  solution,  and  even  the  amounts  of  the  iron 
and  ammonium  salts  present. 
The  precau-         This  fact  must  be  borne   in   mind  when   the   phosphorus   is 

tions  it  ne- 
cessitates,   determined   by   direct   weighing  of  the   phospho-molybdate,   and 

every  effort  must  be  used  to  effect  the  precipitations  always 
under  as  nearly  as  possible  the  same  conditions. 


RAPID  METHODS  FOR   PHOSPHORUS. 


95 


FIG.  51. 


RAPID    METHODS. 

Volumetric   Method.* 

This  method  gives  an  indirect  determination  of  P  by  means 
of  the  estimation  of  the  MoO3  in  the  phospho-molybdate  of 
ammonium,  in  which  form  the  P  is  precipitated.  The  MoO3  is 
reduced  to  a  lower  state  of  oxidation  by  the  reducing  action 
of  Zn  and  H2SO4,  and  the  reduced  oxide  is  titrated  with  a 
standardized  permanganate  solution,  MoO3  being  again  formed 
by  the  reaction. 

Fig.  51  shows  a 
form  of  shaking-ma- 
chine for  shaking  four 
flasks  at  once.  The 
construction  and 
method  of  use  are  ap- 
parent from  the  sketch. 

Fig.  52  shows  a 
form  of  reductor  which 
is  most  convenient  and 
efficient  The  tube  a 
is  0.018  m.  in  inside 
diameter  and  0.300  m. 
long.  The  small  tube 
below  the  contraction 
with  the  stopcock  c  is 
0.006  m.  in  inside  di- 
ameter and  o.ioo  m.  long  below  the  stopcock.  The  tube  is  filled 
by  placing  at  the  point  of  contraction  a  flat  spiral  of  platinum 

*  This  method  is  the  one  prepared  by  the  sub-committee  on  Methods  of  the  Inter- 
national Steel  Standards  Committee  of  the  United  States.  It  is  by  far  the  best  method 
known,  and  the  results  obtained  by  it  are  exceedingly  accurate  when  the  details  are 
carefully  observed.  The  sub-committee  consists  of  W.  P.  Barba,  A.  A.  Blair,  T.  M. 
Drown,  C.  B.  Dudley  (chairman),  and  P.  W.  Shimer. 


96 


ANAL  YSIS   OF  IRON  AND  STEEL. 


wire  which  nearly  fills  the  tube  and  from  the  centre  of  which  a 
perpendicular  wire  extends  downward  a  few  millimetres  into  the 
small  tube.  On  top  of  this  is  placed  a  plug  of  glass  wool,  about 
0.008  m.  thick,  and  then  asbestos,  previously  treated  with  con- 
centrated hydrochloric  acid,  thoroughly  washed,  ignited,  and  dif- 
fused in  water,  is  poured  into  the  reductor  tube  until  it  forms  a 
coating  on  top  of  the  glass  wool  not  over  o.ooi  m.  thick.  This 


FIG.  52. 


FIG.  53. 


makes  a  filter  which  prevents  very  small  pieces  of  zinc  or  other 
materials  from  being  carried  through.  It  is  necessary  to  clean 
and  refill  the  tube  from  time  to  time,  as  the  filter  after  some  use 
becomes  clogged  and  the  liquid  passes  too  slowly.  The  tube  is 
filled  to  within  0.050  m.  of  the  top  with  granulated  amalgamated 
zinc,  and  a  plug  of  glass  wool  is  placed  on  top  of  the  zinc  which 
prevents  all  spattering  of  the  solution  on  the  upper  part  of  the 


RAPID   METHODS  FOR   PHOSPHORUS. 

tube.  The  funnel  b,  which  should  be  not  less  than  o.ioo  m.  in 
diameter  across  the  top,  is  fitted  tightly  into  the  reductor  tube  by 
means  of  a  rubber  stopper,  as  shown  in  the  cut.  The  reductor 
tube  is  fixed  at  such  a  height  that  when  the  block  is  removed 
from  under  the  flask  /,  the  latter  may  be  readily  detached  from 
the  tube  and  removed  without  disturbing  the  apparatus. 

Fig.  53  shows  the  burette  arranged  for  running  the  potassium 
permanganate  directly  into  the  flask  and  needs  no  explanation. 
It  should  be  carefully  calibrated. 

The  various  beakers,  flasks,  graduates,  etc.,  required  by  this 
method  need  no  special  comment. 

Reagents. 

Nitric  Acid. — Nitric  acid  of  1.135  SP-  gr->  made  by  mixing 
C.  P.  nitric  acid  1.42  specific  gravity  with  about  three  parts  of 
distilled  water. 

Strong  Sulphuric  Acid. — The  C.  P.  material  of  1.84  sp.  gr. 

Dilute  Sulphuric  Acid. — Sulphuric  acid  2j^  per  cent.,  by 
volume,  made  by  adding  25  c.c.  of  concentrated  C.  P.  sulphuric 
acid  to  i  litre  of  distilled  water. 

Strong  Ammonia. — The  C.  P.  material  of  0.90  sp.  gr. 

Dilute  Ammonia. — 0.96  sp.  gr.,  made  by  mixing  concentrated 
C.  P.  ammonia  water  of  0.90  sp.  gr.,  with  about  one  and  a  half 
times  its  volume  of  distilled  water. 

Strong  Solution  of  Potassium  Permanganate,  for  oxidizing  the 
phosphorus  and  carbonaceous  matter  in  the  nitric  acid  solution  of 
a  steel.  Made  by  dissolving  12.5  to  15  grammes  of  crystallized 
potassium  permanganate  in  i  litre  of  distilled  water  and  filtering 
through  asbestos. 

Standard  Solution  of  Potassium  Permanganate  for  titrating  the 
reduced  solutions  of  ammonium  phosphomolybdate.  Made  by 
dissolving  2  grammes  of  crystallized  potassium  permanganate  in 
I  litre  of  distilled  water  and  filtering  through  asbestos.  This 
solution  is  standardized  as  follows:  Weigh  into  125  c.c.  Erlen- 

7 


98  ANAL  YSIS   OF  IRON  AND   STEEL, 

meyer  flasks,  three  portions  of  thoroughly  cleaned  soft  steel  wire, 
in  which  the  iron  has  been  carefully  determined,  of  from  0.15  to 
0.25  grammes  each,  and  pour  into  each  of  the  flasks  30  c.c.  of 
distilled  water  and  10  c.c.  of  strong  sulphuric  acid.  Cover  with 
a  small  watch-glass  and  heat  until  solution  is  complete.  Add  a 
sufficient  amount  of  the  strong  solution  of  potassium  permanga- 
nate to  oxidize  the  iron  and  destroy  the  carbonaceous  matter, 
being  careful  to  avoid  an  excess  which  would  cause  a  precipitate 
of  binoxide  of  manganese.  Should  this  occur,  redissolve  it  by 
adding  a  very  few  drops  of  sulphurous  acid  and  boil  off  every 
trace  of  the  latter.  Allow  the  solution  in  the  flasks  to  cool  and 
add  to  each  10  c.c.  of  dilute  ammonia.  Pass  through  the 
reductor  and  titrate  in  the  flask. 

In  all  cases  the  mode  of  procedure  in  using  the  reductor 
should  be  as  follows :  Everything  being  clean  and  in  good  order 
from  previous  treatment  with  dilute  sulphuric  acid,  and  washing 
with  distilled  water,  a  little  of  the  wash  water  being  left  in  the 
neck  of  the  funnel  b  (Fig.  52),  and  the  flask  being  attached  to 
the  filter  pump,  pour  100  c.c.  of  warm  dilute  sulphuric  acid  into 
the  funnel  and  open  the  stopcock  c.  When  only  a  little  remains 
in  the  neck  of  the  funnel,  transfer  the  solution  to  be  reduced  to 
the  funnel.  This  solution  should  be  hot  but  not  boiling.  Pour 
some  of  the  dilute  sulphuric  acid  into  the  vessel  which  contained 
the  solution  to  be  reduced  to  wash  it,  and  when  only  a  little 
solution  is  left  in  the  neck  of  the  funnel  as  before,  add  this  to 
the  funnel  in  such  a  way  as  to  wash  it  and  follow  with  about  200 
c.c.  more  of  warm  dilute  sulphuric  acid  and  finally  with  50  c.c.  of 
hot  distilled  water.  In  no  case  allow  the  funnel  b  to  get  empty, 
and  close  the  stopcock  c  when  there  is  still  a  little  of  the  wash 
water  left  in  the  funnel.  This  precaution  prevents  air  from 
passing  into  the  reductor  tube.  A  blank  determination  is  made 
by  passing  through  the  reductor  a  solution  containing  a  mixture 
of  10  c.c.  strong  sulphuric  acid,  10  c.c.  dilute  ammonia,  and  50 
c.c.  water ;  preceded  and  followed  by  the  dilute  acid  as  described 


RAPID   METHODS  FOR   PHOSPHORUS. 

above.  The  amount  of  potassium  permanganate  required  to  give 
this  blank  a  distinct  color  is  subtracted  from  the  amount  required 
to  give  the  same  color  to  each  reduced  solution. 

To  get  the  value  of  the  permanganate  solution,  multiply  the 
weight  of  iron  wire  taken  by  the  percentage  of  iron  in  the  wire 
and  divide  by  the  number  of  cubic  centimetres  of  potassium  per- 
manganate used  in  the  titration.  This  will  give  the  value  of  I 
c.c.  of  permanganate  in  terms  of  metallic  iron.  Multiply  this 
result  by  0.88163,  the  ratio  of  molybdic  acid  to  iron  and  the 
product  by  0.01794,  the  ratio  of  phosphorus  to  molybdic  acid 
and  the  result  is  the  value  of  I  c.c.  of  the  permanganate  solution 
in  terms  of  phosphorus.  The  ratio  of  molybdic  acid  to  iron 
given  above  is  that  found  when  a  known  amount  of  molybdic 
acid  in  sulphuric  acid  solution  is  passed  through  the  reductor  in 
the  manner  described  above  and  then  titrated  with  potassium 
permanganate  solution  whose  strength  in  terms  of  metallic  iron 
is  known.  The  reduction  of  the  molybdic  acid  in  the  reductor 
in  this  case  is  to  the  form  Mo24O37.  The  ratio  of  phosphorus 
to  molybdic  acid  given  above  is  that  found  by  the  analysis  of 
the  yellow  precipitate  of  ammonium  phosphomolybdate  obtained 
from  nitric  acid  solution  of  iron  under  varying  conditions. 

Sulphurous  Acid. — A  strong  solution  of  the  gas  in  water. 
Siphons  of  the  liquefied  gas  may  be  obtained  in  the  market. 

Acid  Ammonium  Sulphite. — The  strong  C.  P.  solution  of  the 
reagent  diluted  with  10  parts  of  water. 

Ferrous  Sulphate. — Crystals  of  the  salt  free  from  phosphorus. 

These  three  reagents  are  for  reducing  the  excess  of  binoxide 
of  manganese  thrown  down  in  oxidizing  the  carbonaceous  matter 
in  the  nitric  acid  solutions  of  the  steels.  Sulphurous  acid  is 
preferred. 

Molybdate  Solution. — Weigh  into  a  beaker  100  grammes  of 
pure  molybdic  anhydride,  mix  it  thoroughly  with  400  c.c.  cold 
distilled  water  and  add  80  c.c.  strong  ammonia,  0.90  sp.  gr. 
When  solution  is  complete,  filter  and  pour  the  filtered  solution 


100 


ANALYSIS   OF  IRON  AND   STEEL. 

slowly  with  constant  stirring  into  a  mixture  of  400  c.c.  strong 
nitric  acid  1.42  sp.  gr.  and  600  c.c.  distilled  water.  Add  50 
milligrammes  of  microcosmic  salt  dissolved  in  a  little  water, 
agitate  thoroughly,  allow  the  precipitate  to  settle  for  24  hours, 
and  filter  before  using. 

Acid  Ammonium  Sulphate  Solution,  for  washing  the  precipitate 
of  ammonium  phosphomolybdate.  To  I  litre  of  water  add  15  c.c. 
of  strong  ammonia,  0.90  sp.  gr.  and  25  c.c.  strong  sulphuric  acid, 
1.84  sp.  gr. 

Amalgamated  Zinc. — Dissolve  5  grammes  of  mercury  in  25 
c.c.  strong  nitric  acid  diluted  with  an  equal  bulk  of  water,  dilute 
to  250  c.c.  and  transfer  to  a  stout  flask  of  about  1000  c.c.  capacity. 
Pour  into  it  500  grammes  of  granulated  zinc  which  will  pass 
through  a  2O-mesh  sieve,  but  not  through  a  3O-mesh.  Shake  it 
thoroughly  for  a  minute  or  two  and  then  pour  off  the  solution, 
wash  the  zinc  thoroughly  with  distilled  water,  dry,  and  preserve 
in  a  glass  bottle  for  use. 

Operation. 

Weigh  2  grammes,  or  in  case  of  steels  containing  over  0.15 
per  cent,  phosphorus,  I  gramme  of  the  steel  into  a  250  c.c. 
Erlenmeyer  flask,  pour  into  it  100  c.c.  of  nitric  acid  1.135  sp. 
gr.,  and  cover  with  a  small  watch-glass.  Heat  until  the  solution 
is  complete  and  nitric  oxide  is  boiled  off.  Add  10  c.c.  of  the 
strong  potassium  permanganate  solution,  boil  until  the  pink  color 
has  disappeared  and  binoxide  of  manganese  separates.  Continue 
the  boiling  for  several  minutes,  then  remove  from  the  source  of 
heat  and  add  a  few  drops  of  sulphurous  acid,  ammonium  sulphite, 
or  a  small  crystal  of  ferrous  sulphate,  repeating  the  addition  at 
intervals  of  a  minute  until  the  precipitated  binoxide  of  manganese 
is  dissolved.  Boil  two  minutes  longer,  place  the  flask  in  a  vessel 
of  cold  water,  or  allow  it  to  stand  in  the  air  until  it  feels  cool  to 
the  hand,  and  then  pour  in  40  c.c.  of  dilute  ammonia  0.96  sp.  gr. 
The  precipitated  ferric  hydrate  will  redissolve  when  the  liquid  is 


RAPID  METHODS  FOR   PHOSPHORUS.  IOI 

thoroughly  mixed.  When  the  solution  is  about  the  temperature 
of  the  hand,  say  35°  C.,  add  40  c.c.  of  molybdate  solution  at  the 
ordinary  temperature,  close  the  flask  with  a  rubber  stopper,  and 
shake  it  for  five  minutes,  either  by  hand  or  in  the  machine,  Figure 
5 1 .  Allow  the  precipitate  to  settle  for  a  few  minutes,  filter  on  a 
0.090  m.  filter,  and  wash  with  acid  ammonium  sulphate  solution 
until  2  or  3  c.c.  of  the  wash  water  give  no  reaction  for  molyb- 
denum with  a  drop  of  ammonium  sulphide.  Pour  5  c.c.  of 
ammonia  0.90  sp.  gr.  and  20  c.c.  of  water  into  the  flask  to  dis- 
solve any  adhering  ammonium  phosphomolybdate  and  then  pour 
it  on  the  precipitate  in  the  filter,  allowing  the  filtrate  to  run  into 
a  250  c.c.  Griffin's  beaker.  Wash  out  the  flask  and  wash  the 
filter  with  water  until  the  solution  measures  about  60  c.c.  Add 
to  the  liquid  in  the  beaker  10  c.c.  strong  sulphuric  acid  and  pass 
it  through  the  reductor  exactly  in  the  manner  described  for  the 
solutions  of  ferric  sulphate  in  standardizing  the  solution  of  potas- 
sium permanganate.  By  adding  the  strong  sulphuric  acid  to  the 
ammoniacal  solution  immediately  before  passing  it  through  the 
reductor  it  is  heated  sufficiently  by  the  chemical  action  to  insure 
thorough  reduction.  In  washing  be  careful  that  no  air  passes 
into  the  reductor,  and  when  the  water  has  been  drawn  through, 
leaving  a  little  still  remaining  in  the  stem  of  the  funnel,  close  the 
stopcock,  detach  the  flask  F,  wash  off  the  drawn  out  portion 
of  the  reductor  tube  into  it,  and  titrate  the  solution  with  the 
standard  permanganate.  The  reductor  should  be  so  arranged 
that  the  whole  reduction  occupies  about  3  or  4  minutes.  The 
solution  that  passes  through  should  be  bright  green  in  color. 
In  adding  the  permanganate,  the  green  color  disappears  first, 
and  the  solution  becomes  brown,  then  pinkish  yellow,  and  ulti- 
mately colorless.  Continue  the  addition  of  the  permanganate 
drop  by  drop,  shaking  the  flask  vigorously  until  the  solution 
assumes  a  faint  pink  coloration,  which  remains  after  standing 
one  minute.  Subtract  from  the  reading  of  the  burette  the 
amount  given  by  a  blank  determination,  obtained  exactly  as 


IO2  ANAL  YSIS   OF  IRON  AND   STEEL. 

described  under  the  method  given  above  for  standardizing  the 
permanganate  solution,  multiply  the  number  of  c.c.  so  obtained 
by  the  value  of  I  c.c.  in  terms  of  phosphorus,  multiply  by  100 
and  divide  by  weight  taken,  and  the  result  is  the  percentage  of 
phosphorus  in  the  steel. 

When  a  large  number  of  analyses  are  to  be  carried  along  at 
once  the  following  modification  is  recommended :  Obtain  the 
yellow  precipitate  and  dissolve  in  ammonia  exactly  as  described 
above,  except  that  the  solution  is  allowed  to  run  into  the  flask 
in  which  the  precipitation  was  made,  and  the  washing  of  the 
filter  is  continued  until  the  solution  amounts  to  75  c.c.  Add 
now  to  the  flask  5  grammes  of  pulverized  zinc,  100  mesh, 
pouring  it  into  the  flask  through  a  funnel  to  prevent  any  zinc 
clinging  to  the  sides  of  the  flask.  Then  add  to  the  flask  1 5  c.c. 
strong  sulphuric  acid  1.84  sp.  gr.  This  is  most  conveniently 
done  in  practice  by  letting  it  run  in  from  a  glass-stoppered 
burette.  Close  the  flask  at  orfce  with  a  rubber  stopper  carrying 
a  glass  tube  bent  twice  at  right  angles,  the  further  arm  dipping 
into  a  beaker  containing  a  saturated  solution  of  sodium  bicar- 
bonate. The  flask  should  now  stand  undisturbed  for  about 
thirty  minutes,  when,  if  all  action  has  ceased,  it  is  ready  to 
titrate  with  permanganate.  The  solution  should  be  green,  not 
brown.  The  temperature  of  the  solution  at  the  end  of  thirty 
minutes  is  about  40°  C.  and  the  titration  succeeds  best  if  done 
at  this  temperature.  But  the  flask  may  stand  a  couple  of  hours 
without  reoxidation  of  the  reduced  molybdic  acid,  and  may 
then  be  successfully  titrated.  If  the  solution  changes  in  color 
to  brown  the  determination  should  be  rejected,  as  the  result  will 
be  too  low.  A  blank  should  be  made  by  adding  to  another  flask 
65  c.c.  of  water,  10  c.c.  of  dilute  ammonia  0.96  sp.  gr.,  5  grammes 
of  the  lOO-mesh  zinc,  added  in  the  manner  described,  and  15  c.c. 
of  strong  sulphuric  acid  1.84  sp.  gr.  This  flask  should  be  treated 
the  same  as  the  others  and  the  amount  of  permanganate  it  uses 
up  should  be  deducted  from  the  amount  required  by  each  flask 


RAPID   METHODS  FOR   PHOSPHORUS. 

containing  a  test.  When  this  method  is  used  the  reduction  is 
practically  complete  to  Mo2O,  so  that  the  factor  0.85714  must  be 
used  instead  of  0.88163. 

Example. 

0.1745  grammes  of  wire  requires  50.0  c.c.  of  permanganate  to 
give  the  required  color.  A  blank  determination  gave  o.i  c.c.,  so 
that  the  wire  actually  required  49.9  c.c.  permanganate.  The  wire 
contained  99.87  per  cent,  of  iron,  then  0.1745  X  0.9987 -=- 49.9 
equals  0.0034923,  or  i  c.c.  of  permanganate  equals  0.0034923 
grammes  metallic  iron.  Then  multiplying  the  value  in  iron 
by  the  ratio  of  molybdic  acid  to  iron  0.88163  or  0.85714  and  the 
product  by  the  ratio  of  phosphorus  to  molybdic  acid  0.01794, 
we  have  0.0034923  X  0.88163  X  0.01794  equals  0.000055238,  or 
i  c.c.  permanganate  equals  0.000055238  grammes  of  phosphorus. 
Again  the  precipitated  ammonium  phosphomolybdate  from  2 
grammes  of  steel  required  35.6  c.c.  permanganate  less  blank 
o.i  c.c.  equals  35.5  c.c.;  35.5  X-O.OOOO55238  X  100  -H  2  equals 
0.098  per  cent,  phosphorus. 

Notes  and  Precautions. 

It  will  be  observed  that  the  method  given  above  oxidizes  the 
phosphorus  in  the  iron  by  means  of  nitric  acid,  completes  and 
perfects  this  oxidation  and  possibly  neutralizes  the  effect  of  the 
carbon  present  by  means  of  potassium  permanganate,  and  then 
separates  the  phosphoric  acid  from  the  iron  by  means  of  mo- 
lybdic acid.  The  molybdic  acid  in  the  yellow  phosphomolybdate 
is  subsequently  determined  by  means  of  potassium  permanganate, 
the  phosphorus  being  determined  from  its  relation  to  the  molyb- 
dic acid  in  this  precipitate.  The  method  given  above  applies  to 
steel  and  wrought  iron,  but  it  is  not  yet  recommended  for  pig- 
iron. 

It  is  hardly  necessary  to  say  that  all  the  chemicals  and 
materials  used  in  the  analysis  are  assumed  to  be  free  from  im- 
purities that  will  injuriously  affect  the  result. 


IO4 


ANAL  YSIS   OF  IRON  AND   STEEL. 

1.135  SP-  gr-  nitric  acid  apparently  oxidizes  the  phosphorus 
just  as  successfully  as  a  stronger  one,  while  by  its  use  solution 
is  sufficiently  rapid,  and  there  is  less  trouble  during  the  subse- 
quent filtration  due  to  silica. 

The  boiling  of  the  solution  to  remove  nitrous  acid  and  assist 
the  action  of  the  oxidizing  permanganate  seems  to  be  essential. 
Some  steels  may  not  require  10  c.c.  of  the  permanganate  and 
some,  like  washed  metal  high  in  carbon,  may  require  even  more. 
It  is  essential  that  enough  should  be  added  to  cause  a  precipita- 
tion of  binoxide  of  manganese  and  to  give  a  strong  pink  color 
to  the  solution.  This  color  gradually  disappears  on  boiling. 
Less  is  required  if  the  permanganate  is  added  in  small  successive 
portions.  Boiling  two  minutes  after  reducing  the  binoxide  of 
manganese  removes  any  nitrous  acid  that  may  be  formed  by  that 
operation. 

In  washing  the  yellow  precipitate  it  shows  some  disposition  to 
crawl  up  to  the  top  of  the  filter.  Care  should  be  taken  therefore 
to  have  the  filter  fit  the  funnel  so  closely  that  even  if  the  precipi- 
tate does  crawl  over  the  top  it  will  not  be  lost  while  washing  the 
filter  completely  to  the  top.  It  is  very  easy  to  leave  enough 
molybdic  acid  in  the  top  of  the  filter,  even  though  the  washings 
are  tested,  to  cause  an  error  of  .005  per  cent,  in  the  determina- 
tion. 

It  is  best  to  make  up  molybdate  solution  rather  frequently. 
It  is  also  best  to  keep  it  in  the  dark  at  a  temperature  not  above 
28°  to  30°  C.  Much  of  the  so-called  molybdic  acid  of  the  market 
is  molybdate  of  ammonium  or  molybdate  of  some  other  alkali. 
This  fact  cannot  be  ignored  in  making  up  the  molybdate  solution. 
A  series  of  experiments  with  various  molybdic  acids  and  alkaline 
molybdates  obtained  in  the  market,  indicates  that  if  the  amount 
of  molybdic  acid  in  the  solution  is  that  called  for  by  the  formula, 
irrespective  of  whether  this  amount  is  furnished  by  pure  molybdic 
acid  or  by  any  of  the  commercial  molybdates  referred  to,  the  re- 
sult will  be  much  nearer  the  truth  than  if  this  is  not  done.  Good 


RAPID   METHODS  FOR    PHOSPHORUS.  IOjj 

molybdic  acid  is  the  best,  but  the  alkaline  molybdates  can  be 
used.  The  amount  of  molybdic  acid  in  these  molybdates  can 
readily  be  determined  by  dissolving  o.iooo  gramme  in  60  c.c. 
of  water  to  which  10  c.c.  of  dilute  ammonia  has  been  added, 
filtering,  adding  10  c.c.  strong  C.  P.  sulphuric  acid,  and  passing 
through  the  reductor  as  above  described.  The  method  given 
in  the  example  above  enables  the  amount  of  molybdic  acid  to 
be  determined.  If  the  molybdic  acid  as  obtained  in  the  market, 
or  the  ammonia  used  in  dissolving  it,  contains  any  soluble  sili- 
cates, the  resulting  molybdate  solution  will  be  yellowish  in  color 
and  the  determinations  made  with  this  solution  will  be  high, 
owing  apparently  to  ammonium  silicomolybdate  being  dragged 
down  with  the  phosphomolybdate.  Treatment  of  the  molybdate 
solution  with  microcosmic  salt,  as  described,  overcomes  this  diffi- 
culty and  gives  a  perfectly  colorless  molybdate  solution.  A 
molybdate  solution  tinged  with  yellow  should  never  be  used. 
It  will  be  observed  that  the  molybdate  solution  recommended 
above  contains  much  less  nitrate  of  ammonia  than  is  given  by 
many  of  the  formulas  now  in  use.  Experience  shows  that  a 
molybdate  solution  made  on  this  formula  keeps  much  better 
than  those  containing  more  ammonium  nitrate.  It  will  also  be 
observed  that  the  amount  used  for  each  determination  is  less 
than  many  methods  employ.  It  is  believed  that  the  amount 
recommended  is  sufficient  and  that  the  ammonium  nitrate  re- 
quired to  assist  the  formation  of  the  yellow  precipitate  is  fur- 
nished by  the  40  c.c.  of  dilute  ammonia  added  to  the  nitric  acid 
solution  of  the  steel.  Of  course  the  molybdate  solution  recom- 
mended above  cannot  be  used  for  other  work  interchangeably 
with  that  made  on  the  older  formulas,  on  account  of  lack  of 
ammonium  nitrate. 

The  directions  in  regard  to  the  reductor,  both  as  to  making 
and  use,  should  be  strictly  followed.  By  the  use  of  the  stop- 
cock, and  the  amalgamated  zinc,  and  by  keeping  a  little  liquid 
in  the  neck  of  the  funnel,  the  same  blank  can  be  obtained  from 


IO6  ANALYSIS   OF  IRON  AND   STEEL. 

a  reductor  almost  continuously,  even  though  two  or  three  days 
of  standing  intervene  between  blanks.  It  is,  however,  always 
advisable  to  treat  with  dilute  sulphuric  acid  and  wash  before 
using,  even  though  only  one  night  has  elapsed  since  the  last 
previous  use.  If  the  solution  to  be  reduced  does  not  contain 
enough  acid  or  is  not  warm  enough,  the  reduction  will  not  be 
complete.  Care  should  therefore  be  taken  not  to  allow  too  much 
mixing  of  the  dilute  sulphuric  acid  with  the  solution  to  be  re- 
duced, either  in  the  funnel  or  in  the  reductor  tube  itself,  The 
best  asbestos  to  use  is  the  mineral  known  as  actinolite,  but  any 
fibrous  mineral  which  will  act  as  a  filter  and  not  be  dissolved  by 
the  acids  used  may  be  employed.  Glass  wool  alone  will  not  do, 
as  a  good  filter  is  essential  in  order  that  neither  small  particles 
of  zinc  nor  impurities  in  the  zinc  may  be  drawn  down  into  the 
flask  with  the  reduced  solution.  The  consumption  of  zinc  is 
very  small. 

In  testing  with  ammonium  sulphide,  to  see  whether  the  wash- 
ing of  the  yellow  precipitate  is  complete,  good  results  are  ob- 
tained by  putting  two  or  three  drops  of  yellow  ammonium 
sulphide  into  a  few  cubic  centimetres  of  distilled  water,  and 
allowing  the  washings  to  drop  into  this  solution  from  the  stem 
of  the  funnel.  If  iron  is  present  in  the  washings  it  will  show 
while  the  solution  is  still  alkaline.  By  allowing  the  washings 
to  continue  running  into  the  ammonium  sulphide  solution  it 
soon  becomes  acid,  when  molybdenum,  if  any  is  present,  shows 
by  a  more  or  less  brownish  color.  If  the  acid  solution  is  pure 
white  from  separated  sulphur  the  washing  is  complete. 

Since  the  acidity  of  the  solution  in  which  the  yellow  precipi- 
tate is  formed  has  an  influence  on  its  composition,  it  is  quite 
desirable  that  the  sp.  gr.  of  the  1.135  nitric  acid  and  of  the 
0.96  ammonia  should  be  taken  with  some  care.  The  tempera- 
ture at  which  the  figures  are  correct  is  15°  C.  It  is  best  to  use 
the  Westphal  balance  in  determining  these  gravities,  but  failing 
this,  a  sufficiently  delicate  hydrometer  can  be  employed. 


RAPID   METHODS  FOR   PHOSPHORUS, 

In  using  the  reduction  with  5  grammes  of  loo-mesh  zinc,  it 
will  be  observed  that  as  the  zinc  becomes  nearly  all  dissolved 
a  blackish  residue  remains.  This  residue  seems  to  be  metallic 
lead.  It  disappears  slowly  during  the  titration  and  apparently 
uses  up  some  permanganate.  It  takes  a  little  longer  to  secure 
a  satisfactory  end  reaction  with  the  loo-mesh  zinc,  as  the  pink 
color  fades  out  several  times  before  it  will  remain  permanent 
for  one  minute.  It  is  essential  that  air  should  be  excluded 
from  the  flask  after  the  reduction  is  nearly  complete,  and  it 
is  for  this  purpose  that  the  sodium  bicarbonate  solution  is 
used.  A  tendency  to  suck  the  soda  solution  back  into  the 
reducing  flask  will  be  noticed,  due  to  the  cooling  of  the 
flask.  The  reduction  should  be  made  in  a  place  free  from 
draughts. 

With  the  amalgamated  zinc  in  the  reductor  made  as  above 
described  the  blank  generally  uses  up  about  O.I  c.c.  of  the 
standard  permanganate  solution.  The  blank  when  using  the 
reduction  by  means  of  5  grammes  loo-mesh  zinc  usually  amounts 
to  0.6  c.c.  of  the  standard  permanganate,  and  may  be  higher. 
Pulverized  zinc  is  rarely  free  from  sulphides,  and  while  this  seems 
not  to  be  a  very  important  matter,  it  is  nevertheless  not  recom- 
mended to  use,  either  in  the  reductor  or  in  the  flask  reduction,  a 
zinc  that  gives  a  high  blank. 

If  the  amount  of  sulphurous  acid  or  other  reagent  added  to 
the  nitric  acid  solution  to  remove  the  precipitated  binoxide  of 
manganese  is  insufficient,  a  brown  stain  will  be  left  on  the  filter 
paper  after  the  yellow  precipitate  is  dissolved  in  ammonia.  This 
may  occur  even  though  the  nitric  acid  solution  looks  clear,  and 
as  no  harm  can  arise  from  a  slight  excess  of  the  reducing  agent, 
it  is  usually  more  satisfactory  to  add  an  excess.  It  is  not  de- 
sirable to  add  the  reducing  agent  to  the  solution  while  boiling, 
as  under  such  circumstances  it  frequently  boils  over. 

It  is  rather  essential  to  use  the  dilute  sulphuric  acid  warm,  so 
that  the  general  temperature  of  the  reductor  may  be  kept  up. 


IO8  ANALYSIS   OF  IRON  AND   STEEL. 

A  good  method  for  cleaning  the  wire  in  standardizing  the 
potassium  permanganates  is  as  follows :  Take  a  round  lead  pencil 
and  make  a  hole  in  it  with  a  pin  near  the  end.  Insert  the  end  of 
the  wire  in  this  hole  and  revolve  the  pencil  until  there  are  two 
turns  of  the  wire  around  it.  Hold  the  turns  firmly  in  one  hand 
and  cut  the  wire  so  that  about  0.75  m.  will  remain  attached  to 
the  pencil.  Draw  this  wire  through  a  piece  of  folded  fine  sand- 
paper several  times  and  then  several  times  through  a  piece  of 
filter  paper.  Seize  the  wire  near  the  pencil  with  the  filter  paper 
and  cut  off  the  part  which  was  wound  around  the  pencil  and 
remove  it.  Then  insert  the  end  of  the  cleaned  wire  in  the  hole 
and  revolve  the  pencil  with  one  hand,  holding  the  wire  in  the 
filter  paper  in  the  other  hand,  until  it  is  all  wound  loosely  on 
the  pencil.  Push  the  coiled  wire  off  the  end  of  the  pencil.  It 
is  now  in  a  convenient  form  for  weighing. 

Direct  Weighing  of  the  Phospho-Molybdate. 

Instead  of  using  the  volumetric  method,  some  chemists  pre- 
fer  to   weigh   the   yellow  precipitate.     Mr.   Wood's    method*   is 
as  follows  : 
Wood's  Dissolve  1.63  grammes  steel  in  a  six-ounce  Erlenmeyer  flask 

method. 

in  30  c.c.  warm  nitric  acid,  1.2  sp.gr.,  place  the  flask  over  a 
Bunsen  flame  and  evaporate  down  to  10  or  15  c.c.,  hastening  the 
evaporation  by  blowing  a  gentle  current  of  air  into  the  flask. 

Heat  50  c.c.  of  molybdate  solution  to  5O°-55°  C,  add  it  to 
the  solution  in  the  flask,  and  shake  well.  Complete  precipita- 
tion should  take  place  in  from  three  to  five  minutes.  Filter  on 
the  pump  in  a  7  c.m.  Munktell's  No.  I  filter  which  has  been  pre- 
viously washed,  dried  at  100°  C.,  and  weighed.  Wash  with  dilute 
nitric  acid,  suck  dry,  wash  once  with  alcohol  and  thoroughly 
with  ether,  and  place  the  filter  containing  the  precipitate  in  a 
funnel  in  an  air-bath  heated  to  110°  C.  The  funnel  in  the  bath 

*  Communicated  to  the  author.  Mr.  Wood  states  that  the  details  adapting  this 
to  a  "  rapid  method"  were  worked  out  by  Mr.  J.  A.  Nichols,  of  the  Homestead  Works. 


DETERMINATION  OF  MANGANESE. 

is  connected  with  the  exhaust  so  that  the  precipitate  and  filter 
are  thoroughly  dried  in  from  one  to  three  minutes,  according  to 
the  size  of  the  precipitate.  Weigh,  and  I  milligramme  of  precipi- 
tate will  be  equal  to  .001  per  cent,  of  phosphorus  in  the  steel. 

In  the  case  of  pig-iron  and  spiegel,  the  metal  after  solution 
in  nitric  acid,  1.2  sp.  gr.,  is  diluted  with  20  c.c.  water,  5  drops 
of  hydrofluoric  acid  are  then  added,  the  solution  is  boiled  for 
two  or  three  minutes,  filtered  through  asbestos  on  the  pump,  and 
concentrated  to  15  c.c. 

15  c.c.  of  chromic  acid  is  added,  the  solution  is  boiled  down 
again  and  precipitated  as  above.  The  hydrofluoric  acid  prevents 
the  separation  of  gelatinous  silica,  but  does  not  interfere  with 
the  precipitation  of  the  phosphorus. 

This  method  will  not  work  with  ferro-manganese,  as  the 
combined  carbon  is  not  completely  oxidized  to  prevent  the  pre- 
cipitation of  all  the  phosphorus. 

The  solutions  referred  to  above  are  prepared  as  follows: 

Molybdic  acid  solution:  To  1200  c.c.  water  add  700  c.c.  Reagents 
ammonia,  sp.  gr.  0.88,  and  I  pound  molybdic  acid ;  when  the 
molybdic  acid  is  dissolved  add  300  c.c.  nitric  acid,  sp.  gr.  1.42, 
and  cool.  Pour  this  solution  into  a  mixture  of  4800  c.c.  water 
and  2000  c.c.  concentrated  nitric  acid.  Filter  for  use  after 
standing  twenty-four  hours. 

Chromic  acid  solution:  1.42  sp.gr.  nitric  acid  saturated  with 
chromic  acid. 


DETERMINATION  OF  MANGANESE. 

The  Acetate  Method. 

Dissolve  I  gramme  of  drillings  in  15  c.c.  HNO3,  1.2  sp.gr., 
in  a  No.  2  Griffin's  beaker.  Evaporate  to  dryness  in  the  air- 
bath,  and  heat  to  decompose  carbonaceous  matter.  Allow  the 
beaker  to  cool,  add  10  c.c.  HC1,  heat  carefully  until  all  the 


IIO 


ANALYSIS   OF  IRON  AND   STEEL. 


For  steel  and 
iron  ultra- 


Na2co3. 


importance 

of  avoid- 

ing  excess 


Fe2O3  is  dissolved,  evaporate  to  dryness  to  get  rid  of  all  the 
HNO3,  redissolve  in  10  c.c.  HC1,  and  evaporate  carefully  until 
the  solution  is  almost  syrupy.  Dilute  with  cold  water  to  about 
IOO  c.c.,  and  filter  off  the  insoluble  matter,  allowing  the  filtrate 
and  washings  to  run  into  a  No.  6  Griffin's  beaker.  In  the  case 
°f  steel  or  puddled  iron  the  filtration  may  be  omitted,  the  solu- 
^on  being  poured  into  the  large  beaker,  and  the  rinsings  of 
the  small  beaker  added.  To  the  solution  in  the  large  beaker, 
which  should  amount  to  about  200  c.c.,  add  a  solution  of  car- 
bonate  of  sodium  very  slowly,  stirring  vigorously.  The  solution 
will  finally  become  very  dark  red  in  color,  and  the  precipitate 
formed  will  redissolve  very  slowly.  Add  the  solution  of  car- 
bonate of  sodium  2  or  3  drops  at  a  time,  stir  well,  and  allow  the 
solution  to  stand  several  minutes,  to  see  whether  the  precipitate 
will  redissolve  or  not.  When,  under  these  circumstances,  a 
decided  precipitate  remains,  add  2  drops  of  HC1,  stir  well,  and 
allow  the  solution  to  stand  for  some  minutes  ;  if  the  solution 
does  not  clear,  add  2  drops  more,  and  stir  again.  If  the  first 
part  of  the  operation  has  been  carefully  conducted,  this  amount 
of  HC1  will  usually  be  sufficient,  but  if,  for  any  reason,  too 
large  a  precipitate  has  been  formed,  it  may  require  a  few  drops 
more.  It  is  important,  however,  that  no  more  HC1  be  added 
than  just  enough  to  redissolve  the  precipitate  formed  by  the 
carbonate  of  sodium,  and,  to  insure  this,  the  solution  should 
be  well  stirred  and  allowed  to  stand  a  sufficient  length  of  time 
after  each  addition  of  HC1.  The  solution  may  be  so  dark  in 
color  that  it  is  difficult  to  see  when  the  precipitate  does  finally 
disappear,  but  by  standing  the  beaker  on  a  piece  of  white 
paper  the  light  reflected  through  the  bottom  of  the  beaker  will 
greatly  diminish  the  difficulty.  When,  under  this  method  of 
procedure,  the  solution  clears,  add  2  grammes  of  acetate  of 
sodium  dissolved  in  a  few  c.c.  of  water,  stir  well,  and  dilute 
the  solution  to  about  700  c.c.  with  boiling  water.  Heat  it  to 
boiling,  and  allow  it  to  boil  for  about  ten  minutes,  then  remove 


DETERMINATION  OF  MANGANESE.  IU 

it  from  the  tripod,  and  allow  the  precipitated  hydrate  and  basic 
acetate  of  iron  to  settle.  Decant  the  clear,  supernatant  fluid  on  Filtering  off 
a  large  washed  German  filter,  throw  the  precipitate  on,  and 
wash  it  two  or  three  times  with  boiling  water,  allowing  the 
filtrate  to  run  into  a  large  beaker  or  flask,  from  which  it  can 
be  transferred  to  a  platinum  or  porcelain  dish  and  evaporated 
rapidly.  When  the  precipitate  has  drained  quite  dry,  by  means 
of  a  platinum  spatula  transfer  it .  to  the  beaker  in  which  the 
precipitation  was  first  made ;  dissolve  the  precipitate  which 
remains  adhering  to  the  filter,  and  that  which  remains  on  the 
blade  of  the  spatula,  by  pouring  around  the  edge  of  the  filter 
and  on  the  spatula  held  over  it  10  c.c.  HC1  diluted  with  twice 
its  volume  of  hot  water,  allowing  it  to  run  into  the  beaker 
containing  the  precipitate.  Wash  the  filter  free  from  chloride 
of  iron  with  cold  water,  and  heat  the  beaker  containing  the 
precipitate  until  the  latter  is  dissolved.  Cool  the  solution,  and 
repeat  the  precipitation,  filtration,  and  resolution  of  the  pre- 
cipitate precisely  as  in  the  first  case,  adding  this  filtrate  to  the 
first  one.  Precipitate,  filter,  and  wash  a  third  time  in  the  same  Evaporation 
manner,  evaporate  all  the  filtrates  down  together  until  they  are 
reduced  to  about  300  c.c.  in  volume,  and  transfer  this  solution 
to  a  No.  3  beaker. 

If  during  the  evaporation  any  manganese  has  become  oxi- 
dized by  exposure  to  the  air,  it  forms  a  hard  ring  on  the  side 
of  the  capsule,  and  may  be  dissolved,  after  the  solution  is  poured 
into  the  beaker,  by  two  or  three  drops  of  HC1,  and  washed  into 
the  beaker.  Should  any  oxide  of  iron  separate  out,  pour  the 
solution  in  the  capsule  through  a  small  filter,  allowing  it  to  run 
into  the  beaker,  wash  the  precipitate  with  hot  water,  dissolve 
it  in  a  very  few  drops  of  dilute  HC1,  and  let  it  run  into  a  No.  I 
beaker.  Add  just  enough  solution  of  carbonate  of  sodium  to 
precipitate  it,  make  it  faintly  acid  with  acetic  acid,  boil  it,  and 
filter  into  the  main  solution. 

This    solution  now  contains  all  the  manganese,  nickel,  and 


112 


ANALYSIS   OF  IRON  AND   STEEL. 


Separation 
of  Cu,  Ni, 
and  Co 
from  the 
Mn. 


Precipita- 
tion of 
MnO2  by 
Br. 


Precipita- 
tion of  Mn2 
(NH4)2 
P2O8+Aq. 


cobalt  and  the  greater  part  of  the  copper  which  may  have  been 
in  the  metal.  Add  to  it  10  grammes  of  acetate  of  sodium  and 
a  few  drops  of  acetic  acid,  heat  it  to  boiling,  and  pass  a  current 
of  H2S  through  the  boiling  solution  for  fifteen  minutes.  This 
will  precipitate  the  copper,  cobalt,  and  nickel.  Filter  off  the 
black  sulphides,  boil  the  filtrate  to  expel  the  excess  of  H2S,  let 
the  solution  cool  somewhat,  and  add  bromine-water  in  excess. 
If  no  precipitate  forms  at  first,  stand  the  solution,  which  should 
be  colored  by  the  bromine-water,  in  a  warm  place  for  an  hour 
or  two,  to  allow  the  precipitate  of  MnO2  to  separate  out.  If  a 
precipitate  forms  immediately,  add  bromine-water  until,  when 
the  precipitate  settles,  the  solution  is  strongly  colored  by  it,  and 
stand  it  aside  for  an  hour  or  two.  At  the  end  of  this  time,  the 
precipitate  having  settled  and  the  supernatant  fluid  being  still 
colored  by  the  bromine,  heat  it  carefully,  finally  to  boiling,  and 
expel  the  excess  of  bromine;  allow  the  precipitate  to  settle, 
filter,  wash  very  carefully,  and  avoid  stirring  up  the  precipitate 
when  it  is  on  the  filter,  as  it  has  a  tendency  to  go  through. 
Dissolve  the  precipitate  on  the  filter  in  sulphurous  acid  water 
containing  a  little  HC1;  allow  the  solution  to  run  into  a  platinum 
dish,  and  wash  the  filter  well.  A  little  of  the  SO2  water  will 
quickly  dissolve  any  MnO2  which  may  adhere  to  the  beaker  in 
which  it  was  precipitated,  and  this  may  be  poured  on  the  filter. 
Boil  the  solution  in  the  dish  to  expel  the  excess  of  SO2,  add 
5  to  20  c.c.  of  a  clear  filtered  solution  of  microcosmic  salt,  heat 
to  boiling,  and  add,  with  constant  stirring,  NH4HO  drop  by 
drop.  When  the  precipitate  of  phosphate  of  ammonium  and 
manganese  begins  to  form,  stop  adding  NH4HO,  and  stir  until 
the  precipitate  becomes  crystalline.  When  this  change  occurs, 
add  one  more  drop  of  NH4HO ;  the  additional  precipitate  formed 
will  be  curdy,  but  a  few  seconds'  continued  stirring  at  the  boiling 
temperature  will  change  it  to  the  silky  crystalline  condition. 
Continue  the  addition  of  NH4HO  in  exactly  this  manner  until 
the  precipitate  is  all  down  and  further  additions  of  NH4HO  fail 


DETERMINATION   OF  MANGANESE.  n^ 

to  change  the  silky  appearance.  Add  a  dozen  drops  of  NH4HO 
in  excess,  remove  the  dish  from  the  light,  and  stand  it  in  ice- 
water  until  perfectly  cold.  Filter  on  an  ashless  filter,  wash  with  Solution  of 

r       .  f  /•,-  NH4NO3 

cold  water  containing   10  grammes  of  nitrate  of  ammonium  (dis-     for  wash- 
solved  in  water  made  faintly  alkaline  with  NH4HO  and  filtered)     Jj^. 
in    100   c.c.    until    the   filtrate    gives   no    reaction   for    HC1,   dry,     tate- 
ignite,  and  weigh  as  Mn2P2O7,  which  contains  38.74  per  cent.  Mn. 
During  the   precipitation    of  the   phosphate   of  ammonium   and 
manganese  the  stirring  must  not  be  discontinued  for  an  instant, 
as  the  solution  has  a  great  tendency  to  bump  when  the  precipitate 
is  allowed  to  settle.     The  crystalline  condition  of  the  precipitate, 
which  is  absolutely  necessary  for  the  success  of  the  determina- 
tion, can  be  most  readily  brought  about  by  the  means  described 
above.     It  can,  of  course,  be  accomplished  by  adding  an  excess 
of  NH4HO  at  once,  but  it  will  require  much  more  boiling  and 
stirring  than  the  method  above  described.     The  final  precipita- 
tion  as   phosphate  of  ammonium  and    manganese,   due   to    Dr. 
Gibbs,  is  much  the  most  accurate  method  known.     A  common 
practice,  however,  is  to  wash  the  bromine  precipitate  of  hydrated  weighing  as 
binoxide  of  manganese,  dry,  ignite,  and  weigh  as  Mn3O4,  which 
contains  72.05  per  cent.  Mn.      There  are  two  objections  to  this  objections 

to  this. 

method  of  procedure :  first,  the  difficulty  of  washing  the  MnO2 
free  from  sodium  salts ;  secondly,  the  uncertainty  as  to  the  exact 
state  of  oxidation  of  the  ignited  oxide  of  manganese.  The  first 
of  these  objections  Eggertz  claims  to  overcome  by  washing  the 
precipitated  MnO2  with  water  containing  I  per  cent,  of  HC1. 
It  may  also  be  overcome,  or  rather  the  danger  may  be  avoided, 
by  using  no  fixed  alkalies.  By  this  method,  nearly  neutralize 
the  HC1  solution  of  the  iron  or  steel  by  NH4HO,  then  add  a 
solution  of  carbonate  of  ammonium  exactly  as  directed  above 
for  carbonate  of  sodium,  and  finally,  instead  of  acetate  of  sodium,  Avoidmgus* 
add  acetate  of  ammonium  (5  c.c.  of  NH4HO  slightly  acidulated  alkalies, 
by  acetic  acid).  Evaporate  the  filtrates  obtained  in  this  way  to 
about  500  c.c.,  transfer  to  a  flask  of  about  I  litre  capacity,  and 

8 


114 


ANAL  YSIS   OF  IRON  AND   STEEL. 


Variable 
composi- 
tion of 
ignited 
oxide  of 
manga- 
nese. 


Weighing 
as  MnS. 


Source  of 
error  in 
acetate 
method. 


Amount  of 
NaC2H302 
necessary. 


cool.  When  perfectly  cold,  add  3  or  4  c.c.  bromine,  shake  well, 
and  when  the  solution  is  strongly  colored  all  through  by  bro- 
mine, add  an  excess  of  NH4HO,  and  heat  to  boiling.  Filter, 
wash  with  hot  water,  dry,  ignite,  and  weigh  as  Mn3O4. 

The  second  objection  seems,  according  to  Pickering,*  to  be 
well  founded,  the  amount  of  manganese  in  the  ignited  oxides 
varying  from  69.688  per  cent,  to  74.997  per  cent.,  according  to 
the  temperature  to  which  they  were  heated  and  other  undeter- 
mined conditions.  This  cause  of  error  may  be  avoided  by 
weighing  the  precipitate  as  MnS,  containing  63.18  per  cent.  Mn. 
This  method,  due  to  H.  Rose,f  is  carried  out  as  follows  :  Ignite 
the  oxide  in  a  porcelain  crucible,  allow  it  to  cool,  mix  it  with 
5  or  6  times  its  volume  of  flowers  of  sulphur,  place  the  crucible 
on  a  triangle,  and  insert  the  bowl  of  a  clay  tobacco-pipe,  which 
should  be  large  enough  to  quite  fill  the  top  of  the  crucible  and 
too  large  to  reach  to  the  precipitate.  Pass  through  the  stem 
a  current  of  dry  hydrogen  until  all  air  is  expelled,  heat  the 
crucible  gradually  to  as  high  a  heat  as  a  good  Bunsen  burner 
will  produce,  cool  in  the  current  of  hydrogen,  and  weigh  as 
MnS. 

General  Remarks  on  the  Acetate  Method. 

The  chief  source  of  error  in  the  acetate  method,  as  it  is 
usually  practised,  is  in  the  addition  of  too  much  acetate  of 
sodium,  whereby  the  manganous  chloride  is  changed  to  manga- 
nous  acetate,  which,  according  to  Kessler,J  is  readily  decomposed 
to  manganous  oxide  and  acetic  acid.  Under  these  circumstances, 
a  larger  amount  of  manganese  is  precipitated  with  the  iron  than 
would  be  the  case  if  a  less  amount  of  acetate  of  sodium  were 
added.  When  acetate  of  sodium  is  added  to  ferric  chloride,  the 
reaction  may  be  written,  6NaC2H3O2,3H2O  +  Fe2Q6==6NaCl-f- 
Fe2(C2H3O2)6+3H2O;  and  to  precipitate  the  iron  as  ferric  acetate 


*  Chem.  News,  xliii.  226. 
\  Chem.  News,  xxvii.  14. 


f  Rose,  Quant.  Anal.  (French  ed.),  p.  104. 


DETERMINATION  OF  MANGANESE.  n- 

in  i  gramme  of  metal  would  necessitate  the  use  of  8  grammes 
of  acetate  of  sodium.  But,  as  Kessler  in  the  same  article 
remarks,  when  a  solution  of  ferric  chloride  is  treated  with  car- 
bonate of  sodium  and  HC1  exactly  as  described  above,  a  liquid 
is  formed  which  contains  14  times  its  equivalent  of  ferric  hydrate 
in  solution.  Consequently  ^  gramme  of  acetate  of  sodium  would 
be  sufficient  to  precipitate  I  gramme  of  iron  as  ferric  hydrate 
and  basic  acetate.  In  order,  however,  to  precipitate  the  manga- 
nese as  MnO2  by  bromine,  it  is  necessary  to  convert  all  the  man- 
ganous  chloride  into  manganous  acetate :  consequently  an  excess 
of  acetate  of  sodium  is  added  before  adding  bromine.  If,  when 
making  the  acetate  precipitation,  the  solution  contains  any  ferrous 
chloride,  a  "brick-dust"  precipitate  is  usually  formed,  which  Brick-dust 
generally  passes  through  the  filter,  and  is  very  difficult  to  dis-  tate. 
solve  or  manage  in  any  way.  It  is  usually  the  shortest  and  best 
plan,  in  this  event,  to  start  a  fresh  portion  and  throw  away  the 
other. 

The  Nitric  Acid  and  Chlorate  of  Potassium  Method. 
(Ford's  Method^ 

The  acetate  method  is  at  best  very  tedious,  and  when  the 
amount  of  manganese  is  very  small  it  is  of  course  desirable  to 
work  on  larger  amounts  than  I  gramme  of  the  sample,  but  the 
iron  precipitate  in  this  event  is  so  large  that  it  becomes  very 
difficult  to  manage  it  properly.  With  Ford's  method,  however, 
there  is  almost  no  limit  to  the  amount  which  can  be  operated 
upon,  and  many  experiments  have  shown  that  with  proper  pre- 
cautions it  is  an  extremely  accurate  process.  The  reaction  on 
which  the  process  is  based  was  first  noticed  by  Hannay*  in  1878; 
but  Fordt  first  worked  out  the  method  in  its  present  practical 

Method  for 

form.      Dissolve   5   grammes  of  borings   in  a  No.   3   beaker  in     steel  and 

puddled 

60  c.c.  HNO3,   1.2  sp.  gr.,  evaporate  down  until  the  solution  is     iron. 

*  Jour.  Chem.  Soc.,  xxxiii.  269.  f  Trans.  Inst.  Min.  Engineers,  ix.  397. 


ANALYSIS   OF  IRON  AND   STEEL. 


Filtering  the 
cold  solu- 
tion. 


Effect  of 
N2O3  in 
HN03. 


Separation 
from  small 
amounts  of 
Fe203  by 
NH4HO. 


almost  syrupy,  then  add  100  c.c.  strong  HNO3,  1.4  sp.  gr.,  and 
5  grammes  KC1O3.  Stand  the  beaker  on  a  tripod  with  a  thin 
piece  of  sheet  asbestos,  about  I  inch  (25  mm.)  in  diameter,  in 
the  centre  of  the  wire  gauge  or  on  the  air-bath,  and  heat  the 
solution  to  boiling.  Boil  the  solution  fifteen  minutes,  remove 
the  light,  add  50  c.c.  strong  HNO3  and  5  grammes  KC1O3, 
replace  the  light,  and  boil  fifteen  minutes  longer,  or  until  the 
yellowish  fumes  from  the  decomposition  of  the  KC1O3  are  no 
longer  given  off.  Cool  the  solution  as  rapidly  as  possible  by 
standing  the  beaker  in  cold  water,  filter  on  the  pump,  using  the 
cone*  or  glass  filtering-tube  with  asbestos  filter,  f  and  wash  two 
or  three  times  with  strong  HNO3,  which  must  be  free  from 
nitrous  fumes.J  Nitrous  acid  reduces  MnO2  to  MnO,  which  then 
dissolves  in  HNO3.  Its  presence  may  be  recognized  by  the 
yellow  color  it  imparts  to  HNO3,  and  it  may  be  removed  by 
blowing  air  through  the  acid.  It  is  always  formed  in  HNO3 
which  has  been  exposed  to  sunlight,  and  for  that  reason  this 
acid  should  be  kept  in  a  dark  place.  Suck  the  precipitate  dry, 
and  transfer  it,  with  the  asbestos  filter,  to  the  beaker  in  which 
the  precipitation  was  made.  Pour  into  the  beaker  10  to  40  c.c. 
strong  sulphurous  acid  water,  which  will  dissolve  the  precipitate 
almost  instantly.  By  pouring  it  through  the  cone  or  filtering- 
tube,  any  adhering  precipitate  will  be  dissolved  and  carried  into 
the  beaker.  As  soon  as  the  precipitate  is  dissolved,  add  2  to  5 
c.c.  HC1,  and  filter  from  the  asbestos  into  a  No.  I  beaker,  wash- 
ing with  hot  water.  Heat  the  filtrate  until  the  excess  of  SO2 
is  driven  off,  add  bromine-water  until  the  solution  is  strongly 
colored  with  it,  and  boil  off  the  excess  of  bromine.  Add  NH4HO 
until  the  solution  smells  quite  strongly  of  it,  boil  for  a  few 
minutes,  and  filter  into  a  No.  3  beaker.  Wash  several  times  with 

*  See  page  26.  f  As  described  under  Methods  for  Determination  of  Carbon. 

J  It  is  always  well  to  transfer  the  filtrate  and  washings  to  a  No.  4  beaker,  add  2 
grammes  KC1O3,  and  boil  again,  to  see  whether  any  further  precipitate  of  MnO2  is 
formed. 


DETERMINATION  OF  MANGANESE. 

hot  water,  remove  the  beaker,  dissolve  the  ferric  hydrate  on 
the  filter  in  dilute  hot  HC1  (l  part  of  acid  to  3  of  water), 
allowing  the  solution  to  run  back  into  the  beaker  in  which  the 
precipitation  was  made,  and  wash  the  filter  with  hot  water.  Boil 
this  filtrate  for  a  few  minutes  to  drive  off  the  chlorine  which 
may  be  present  from  the  solution  of  any  little  MnO2  precipitated 
with  the  ferric  hydrate,  reprecipitate  by  NH4HO  as  before,  filter, 
and  repeat  the  solution,  precipitation,  and  filtration,  allowing  all 
the  filtrates  from  the  ferric  hydrate  to  run  into  the  No.  3  beaker. 
Acidulate  this  solution,  which  will  be  about  300  or  400  c.c.  in 
volume,  with  acetic  acid,  heat  to  boiling,  and  pass  H2S  through 
the  boiling  solution  for  ten  or  fifteen  minutes.  Filter  into  a  Separation 
platinum  dish  from  any  sulphide  of  cobalt,  which  is  the  only  baU. 
metal  likely  to  be  present  with  the  manganese ;  boil  off  the  H2S 
after  adding  a  little  HC1,  add  microcosmic  salt,  and  precipitate, 
filter,  ignite,  and  weigh,  as  directed  on  pages  112  and  113,  as 
Mn2P2O7. 

Steels  containing  much  Silicon. 

In  steel  high  in  silicon,  0.2  per  cent,  and  over,  the  gelatinous 
silica  formed  is  very  apt  to  clog  the  filter  when  operating  as 
described  above,  and  it  is  better  to  dissolve  the  sample  in  HC1, 
evaporate  to  dryness,  being  careful  not  to  heat  it  too  hot,  redis- 
solve  carefully  in  50  c.c.  strong  HNO3,  boil  down  until  nearly 
syrupy  to  destroy  all  the  HC1,  redissolve  in  100  c.c.  strong 
HNO3,  and  precipitate  as  directed  above. 

Instead  of  dissolving  in  HC1,  Mr.  Wood  suggests  adding  a 
few  drops  of  hydrofluoric  acid  to  the  nitric  acid  solution  before 
evaporating.  This  seems  to  work  extremely  well,  and  saves 
much  time  in  the  case  of  high  silicon  steels.  It  may  also  be  Si°»- 
used  to  advantage  in  the  case  of  pig-iron  instead  of  the  method 
given  below. 

Pig-iron. 

Dissolve  5  grammes  in  50  c.c.  dilute  HC1  (i  part  HC1  to  I 
part  water),  filter  on  a  washed  German  filter  into  a  No.  3  beaker, 


US  ANALYSIS   OF  IRON  AND   STEEL. 

evaporate   to    dryness,   redissolve   in   50  c.c.   strong    HNO3,   and 
proceed  as  in  the  case  of  "  steel  high  in  silicon." 

Spiegel  and  Ferro-manganese. 

It  is  best  to  use  only  I  gramme  of  spiegel  or  ferro-manganese 

of  20  to  40  per  cent,  manganese  and  .5  gramme  of  very  high,  60 

Variation  in    to  8o  per  cent,  ferro-manganese.     In  the  latter,  indeed,  it  is  better 

methodfor  to  use  the  acetate  method  with   NH4HO  and  NH4C2H3O2,  and, 

ga^esT*""  omitting   the   precipitation   by   bromine,   boil    off  the    H2S    from 

the  nitrate  from  the   insoluble   sulphides,  after  adding  HC1,  and 

then  precipitate  by  microcosmic  salt  as  directed  above. 

RAPID  METHODS. 
Volumetric  Methods. 

Volhard's  Method* 

This  method  is  based  on  the  principle  announced  by  Moraw- 
ski  and  Stingl,f  that  when  permanganate  of  potassium  is  added 
to  a  neutral  manganous  salt  all  the  manganese  is  precipitated, 
in  accordance  with  the  reaction  4KMnO4  -j-  6MnSO4  +  4H2O  = 
ioMnO2  +  4KHSO4+2H2SO4.  When  all  the  manganous  salt 
is  oxidized,  the  solution  is  colored  by  the  permanganate,  which 
thus  indicates  the  end  reaction.  The  permanganate  used  for 
titrating  iron  ores  may  be  used  for  this  determination,  and,  its 
value  being  determined,  as  directed,  in  terms  of  Fe,  the  cal- 
Caicuiation  culation  for  Mn  is  as  follows  :  The  reaction,  when  perman- 
ofperman-  ganate  is  added  to  a  solution  of  ferrous  sulphate,  is  ioFeSO4-|- 
ganate"  0  8H0  or  2 


molecules  of  permanganate  oxidize  10  molecules  of  FeSO4.  Now, 
as  2  molecules  of  permanganate  oxidize  3  molecules  of  man- 
ganous sulphate,  while  2  molecules  of  permanganate  oxidize  10 
molecules  of  ferrous  sulphate,  the  oxidizing  power  of  the  per- 

*  Liebig's  Annalen,  Band  cxcviii.  p.  318;   Chem.  News,  xl.  207. 
•j-  Chem.  News,  xxxviii.  297. 


RAPID  METHODS  FOR   MANGANESE.  U 

manganate  is  only  three-tenths  as  great  in  the  former  case  as  it  is 
in  the  latter,  and  its  value  in  Mn  is  to  its  value  in  Fe  as  3  is  to 
10,  or  |-|  X  YQ  =  iro"-  Therefore  the  value  of  the  permanganate  Details 
in  Fe  multiplied  by  £|-|  or  0.2946==  its  value  in  Mn.  Dissolve  method. 
1.5  grammes  of  borings  in  a  platinum  or  porcelain  dish  in  25 
c.c.  HNO3,  1.2  sp.  gr.  When  solution  is  complete,  add  12  c.c. 
dilute  H2SO4  (i  part  concentrated  H2SO4  and  I  part  water),  and 
evaporate  to  dryness,  as  directed  on  page  20,  heating  until 
fumes  of  H2SO4  are  given  off  in  order  to  destroy  all  the  car- 
bonaceous matter.  Or  dissolve  in  HNO3  as  above,  evaporate 
to  dryness,  and  heat  on  the  tripod  until  the  carbonaceous 
matter  is  destroyed;  dissolve  in  15  c.c.  HC1,  add  12  c.c.  dilute 
H2SO4  as  above,  and  evaporate  until  fumes  of  H2SO4  are  given 
off.  Allow  the  dish  to  cool,  add  100  c.c.  water,  and  heat  until 
all  the  ferric  sulphate  is  dissolved.  Wash  into  a  carefully 
graduated  300  c.c.  flask,  so  that  with  the  washings  the  solution 
may  not  exceed  200  c.c.  in  volume,  and  add  solution  of  car- 
bonate of  sodium  until  the  precipitate  which  is  first  formed 
dissolves  only  with  difficulty.  Then  add  slowly  zinc  oxide* 
suspended  in  water,  shaking  well  after  each  addition  until  the 
iron  is  precipitated,  which  will  be  shown  by  the  sudden  coagu- 
lation of  the  solution.  The  precipitate  will  then  settle,  leaving 
a  slightly  milky  supernatant  liquid.  Fill  the  flask  exactly  to 
the  mark  on  the  neck  (300  c.c.),  and  mix  thoroughly  by  pour- 
ing the  entire  contents  of  the  flask  into  a  large,  clean,  dry 
beaker,  and  back  again  into  the  flask,  repeating  this  several 
times.  Allow  the  precipitate  to  settle  for  a  few  minutes,  and 
pour  the  solution  through  a  large,  dry  filter.  Fill  a  200  c.c. 
pipette  with  this  filtrate,  which  will,  of  course,  represent  exactly 
I  gramme  of  the  sample,  run  it  into  a  flask  of  about  500  c.c. 
capacity,  heat  to  boiling,  and  add  2  drops  of  HNO3,  sp.  gr.  1.2. 
Now  add  permanganate  solution  slowly  from  a  burette,  shaking 

*  See  page  58. 


12Q  ANALYSIS   OF  IRON  AND   STEEL. 

after  each  addition  to  mix  the  solution  and  facilitate  the  collec- 
tion of  the  precipitated  hydrated  peroxide  of  manganese.  When 
the  reaction  is  nearly  finished,  the  solution  will  be  slightly  col- 
ored by  the  permanganate,  but  the  color  disappears  after  shaking 
the  flask  and  allowing  it  to  stand  for  a  moment.  Finally,  how- 
ever, a  drop  or  two  will  give  the  solution  a  permanent  pink  color, 
which  will  not  disappear  for  several  minutes.  The  number  of  c.c. 
of  the  permanganate  solution  used  multiplied  by  the  factor  found 
(the  Fe  factor  of  the  permanganate  multiplied  by  .2946)  is  the 
amount  of  manganese  in  the  sample.  If,  during  the  addition 
of  the  permanganate,  the  solution  should  become  cool  and  the 
precipitate  fail  to  collect  and  settle  quickly,  heat  the  solution, 
Applicable  but  not  quite  to  the  boiling-point.  This  method  is  applicable 

except 

for  very      for  all  samples  except  those  containing  very  minute  amounts  of 
TmTunts     manganese.     In  working  on  spiegel,  take  .75  gramme,  then,  using 
ofMn-       two-thirds   of  the  filtrate,   the    amount  will   be   calculated   on   .5 
gramme. 

Williams' s  Method. 

This  method,  which  consists  in  precipitating  the  MnO2  by 
Ford's  method,  filtering,  washing,  dissolving  in  H2SO4  with  a 
measured  volume  of  some  reducing  agent,  such  as  oxalic  acid 
or  ferrous  sulphate,  and  titrating  the  excess  by  permanganate, 
was  first  used  by  Williams.*  Regarding  the  precipitate  by  KC1O3 
in  a  nitric  acid  solution  as  MnO2,  the  reaction  in  dissolving  it 
might  be  expressed  thus:  MnO2-f-  2FeSO4  +  2H2SO4=MnSO4-r- 
Fe2(SO4)3  +  2H2O,  or  MnO2  +  H2C2O4  +  H2SO4  =  MnSO4  +  2CO2 
Oxidizing  -f-2H2O.  Therefore  I  molecule  of  MnO2  oxidizes  2  molecules 

power  of 

MnO2.  of  ferrous  sulphate  or  I  molecule  of  oxalic  acid,  and,  the  excess 
of  oxalic  acid  or  ferrous  sulphate  unoxidized  having  been  de- 
termined by  a  solution  of  permanganate,  the  difference  between 
this  excess  and  the  amount  originally  added  is  the  amount 
oxidized  by  the  MnO2. 

*  Trans.  Inst.  Min.  Engineers,  x.  100. 


RAPID   METHODS  FOR   MANGANESE.  12\ 

We  therefore  require  two  standard  solutions,  one  of  perman-  standard 

solutions 

ganate  and  one  of  ferrous  sulphate,  ammonium  ferrous  sulphate,  required, 
or  oxalic  acid.  The  permanganate  solution  used  for  iron  deter- 
minations answers  perfectly.  A  solution  of  ferrous  sulphate  is 
perhaps  the  most  satisfactory,  and  is  prepared  by  dissolving  10 
grammes  of  the  crystallized  salt,  FeSO4,7H2O,*  in  900  c.c.  water 
and  100  c.c.  strong  H2SO4.  It  will  keep  perfectly  in  a  glass- 
stoppered  bottle  in  the  dark  for  a  long  time.  One  c.c.  of  this 
solution  will  be  equal  to  about  .002  gramme  Fe,  or  nearly  .001 
gramme  Mn,  and  if  the  permanganate  is  of  the  usual  strength, 
say  I  c.c.  =  .007  gramme  Fe,  I  c.c.  of  the  permanganate  will 
equal  about  3.5  c.c.  of  the  ferrous  sulphate.  The  permanganate  standard- 
solution  having  been  carefully  standardized,  measure  50  c.c.  of  the  solutions. 
ferrous  sulphate  solution  by  means  of  a  pipette  into  the  dish,f 
dilute  to  about  I  litre,  and  run  in  permanganate  solution  from  a 
burette,  stirring  constantly  until  the  first  permanent  pink  tint 
appears.  The  reading  of  the  burette  will  give  the  value  of  50  c.c. 
ferrous  sulphate  in  permanganate,  and  consequently  by  a  simple 
calculation  its  value  in  Fe  and  Mn.  Suppose,  for  instance,  I  c.c. 
permanganate  solution  =  .0068  gramme  Fe,  or  (according  to  the 
proportion  given  above,  1 12  :  55  : :  Fe  :  Mn)  =  .00334  gramme  Mn. 
Then  if  14.1  c.c.  permanganate  =  50  c.c.  ferrous  sulphate,  100  c.c. 
ferrous  sulphate  will  be  equivalent  to  28.2  c.c.  permanganate. 
In  using  oxalic  acid,  dissolve  2.25  grammes  of  the  crystallized 
acid,  H2C2O4,2H2O,  in  I  litre  of  water,  and  determine  its  strength 
by  measuring  50  c.c.  into  the  dish,  diluting  with  hot  water, 
adding  5  c.c.  H2SO4,  and  titrating  with  permanganate. 

The    details    of  the    method  are   as    follows :    Weigh    out    5    Details 
grammes  of  the  sample  of  puddled  iron,  pig-iron,  or  steel,  and     method. 
proceed   as    directed   on  p.    116  et  seq. ;   but   after  filtering  and 
washing  the  precipitated  MnO2  with  strong  HNO3,  suck  the  pre- 
cipitate  as   dry  as   possible,  and  then  wash   out  the  beaker  in 

*  See  page  55.  f  See  Determination  of  Iron  in  Iron  Ores. 


122 


ANALYSIS   OF  IRON  AND   STEEL. 


which  the  precipitation  was  made  with  cold  water.  Pour  this 
water  on  the  precipitate,  and  repeat  the  operation  two  or  three 
times  to  get  rid  of  all  the  HNO3.  Suck  the  precipitate  as  dry 
as  possible,  transfer  it  with  the  asbestos  to  the  beaker  in  which 
the  precipitation  was  made,  measure  into  the  beaker  100  c.c. 
of  the  standard  ferrous  sulphate  solution  (or  TOO  c.c.  oxalic  acid 
solution  and  10  c.c.  H2SO4),  and  stir  until  the  MnO2  is  all  dis- 
solved. When  using  oxalic  acid  it  is  necessary  to  heat  gently 
to  about  60°  C.  Wash  the  solution  and  asbestos  into  the  dish, 
dilute  to  about  I  litre  (with  oxalic  acid  use  hot  water),  and  titrate 

with  permanganate.    We  will  sup- 
FIG.  54. 
Example.  ^  pose,  for  example,  that  it  requires 

10.2  c.c.  permanganate  to  give  the 
permanent  rose  tint;  then,  as  100 
c.c.  ferrous  sulphate  —  28.2  c.c. 
permanganate,  there  would  be  the 
equivalent  of  28.2  —  10.2  =  18  c.c. 
of  permanganate  in  ferrous  sul- 
phate oxidized  by  the  MnO2  pre- 
cipitate. One  c.c.  of  permanga- 
nate being  equivalent  to  .00334 
gramme  Mn,  18  c.c.  =  .06012 
gramme  Mn,  and,  5  grammes  of 
the  sample  having  been  taken, 
.06012  -5-  5  =  .01202  X  ioo  — 
1. 202  per  cent.  Mn. 

Fig.    54    shows    a    very    con- 
Apparatus     venient  piece   of  apparatus   designed   by  Mr.  E.  A.   Uehling    in 

for  ferrous 

sulphate         1 884-* 

It  is  especially  useful  when  it  is  necessary  to  rapidly  add  a 
constant  volume  of  a  standard  reagent,  for  instance,  a  measured 


*  Communicated   to   the    author   by  Mr.   A.   L.   Colby,  of  the  Bethlehem  Iron 
Company. 


RAPID  METHODS  FOR   MANGANESE.  12$ 

excess  of  ferrous  sulphate  in  volumetric  determination  of  man- 
ganese after  precipitation  with  potassium  chlorate. 

The  burette-tube  extends  to  the  bottom  of  the  Wolff  bottle, 
which  holds  2  litres.  Enough  air  is  supplied,  without  danger  of 
dust  or  evaporation  of  solution,  by  means  of  a  pin-hole  drilled 
in  the  neck  of  the  bottle  and  through  the  hollow  glass-stopper. 
The  bottle  may  be  blackened  to  preserve  the  solution  from  the 
action  of  light. 

Spiegel  and  Ferro-manganese. 

When  working  on  spiegel  or  ferro-manganese,  take  .5  gramme 
of  the  sample  and  proceed  in  the  same  manner  as  directed  for 
steel  or  iron ;  but  it  is  better  to  use  a  standard  solution  of  ferrous 
sulphate  containing  30  grammes  of  FeSO4,7H2O  to  the  litre  for 
very  high  ferro-manganese. 

As  there  seems  to  be  some  uncertainty  as  to  the  exact  com-  composition 
position  of  the  oxide  of  manganese,*  the  permanganate  solution     ideof 


may  be  standardized  as  follows :  Determine  the  absolute  amount 
of  manganese  in  a  finely-ground  and  well-mixed  sample  of  spiegel 
or  ferro-manganese  by  a  gravimetric  method,  then  treat  .5  gramme  standard- 
of  the  same  sample  exactly  as  described  above,  and,  having  found  spiegei  of 
the  number  of  c.c.  of  permanganate  that  are  equivalent  to  100  c.c. 
of  the  ferrous  sulphate  solution,  the  amount  of  manganese  in  the 
sample  divided  by  the  number  of  c.c.  of  permanganate  equivalent 
to  the  ferrous  sulphate  oxidized  by  the  oxide  of  manganese  in 
the  sample,  gives  the  value  of  the  permanganate  solution.  Thus, 
if  100  c.c.  ferrous  sulphate  solution  require  28.2  c.c.  permanganate 
to  give  the  rose  tint  upon  titration,  the  sample  of  spiegel  con- 
tains 14.50  per  cent.  Mn,  and  the  ferrous  sulphate  remaining  after 
the  solution  of  the  oxide  of  manganese  in  100  c.c.  requires 
6.5  c.c.  permanganate  to  give  the  rose  tint  upon  titration  (using 

*  Stone,  Trans.  Inst.  Min.  Engineers,  xi.  323,  xii.  295,  514;    Mackintosh,  Trans. 
Inst.  Min.  Engineers,  xii.  79,  xiii.  39. 


124 


ANALYSIS   OF  IRON  AND   STEEL. 


.5   gramme  of  the  sample,  of  which    i    gramme  contains   .1450 
Example.      gramme  Mn),  the  calculation  would  be  as  follows:   28.2  c.c.— 
6.5   c.c.  =  21.7  c.c.  =  .0725    gramme  Mn,  or  i  c.c.  permanganate 
is  equivalent  to  '^jf  =.00334  gramme  Mn. 


Deshays's  Method* 

This  method  is  based  on  the  fact  that  nitrate  of  manganese, 
when  boiled  with  excess  of  nitric  acid  and  peroxide  of  lead,  is 
oxidized  to  permanganic  acid,  which  is  reduced  again  by  a 
standard  solution  of  arsenite  of  sodium. 

Dissolve  .5  gramme  of  steel  or  pig-iron  in  a  No.  o  Griffin's 
beaker,  or  in  a  test-tube,  in  30  c.c.  nitric  acid,  1.2  sp.  gr.,  and 
boil  until  solution  is  complete  and  the  evolution  of  nitrous 
fumes  ceases.  Remove  from  the  burner,  and  add  cautiously  1-3 
grammes  of  dioxide  of  lead,  or  red  lead,  free  from  manganese, 

Washing  the  and  dilute  with  hot  water  to  about  60  c.c.  Heat  the  solution  to 
dpitate.  boiling,  and  as  soon  as  it  commences  to  boil  stand  the  beaker 
or  test-tube  aside  and  allow  the  lead  salt  to  settle.  When  tol- 
erably clear,  decant  the  solution  and  boil  the  residue  with  50  c.c. 
nitric  acid  and  water  (i  part  acid  to  3  parts  water).  Decant 
as  before,  and  repeat  the  operation  until  the  supernatant  fluid  is 
colorless.  Filter  the  decantations  through  asbestos  and  titrate 
with  a  standard  solution  of  arsenite  of  sodium.  The  standard 
solution  may  be  prepared  of  a  convenient  strength  by  dissolving 
4.96  grammes  of  arsenious  acid  together  with  25  grammes  of 
carbonate  of  sodium  in  water  and  diluting  to  2-2^  litres. 

standard-  To  standardize  this  solution,  treat  a  steel  containing  a  known 

arsenite  of  amount  of  manganese,  as  described  above,  and  calculate  the  value 

solution      °f  eacn  c-c-  °f  the  standard  solution  by  dividing  the  per  cent. 

of  manganese    in    the  steel   by  the  number  of  c.c.   required   to 

destroy  the  color  of  the  permanganic  acid.     Or  take  a  measured 

quantity  of  a   standardized  solution  of  permanganate  of  potas- 

*  Bull.  Soc.  Chim.  de  Paris,  June  20,  1878. 


RAPID   METHODS  FOR   MANGANESE.  I2 

sium  and  see  how  many  c.c.  of  the  arsenite  of  sodium  are  equal 
to  I  c.c.  of  the  permanganate  solution.  Then  the  value  of  the 
permanganate  solution  in  iron,  multiplied  by  11/56  is  equal 
to  its  value  in  manganese,  according  to  the  equation, 

ioFeS04  +  2KMn04  +  8H2SO4  =  5Fe2(SO4)3  +  K2SO4  +  2MnSO4 

+  8H20, 

or  10  atoms  of  Fe  correspond  to  2  atoms  of  Mn,  or  560  parts 
by  weight  of  Fe— no  parts  by  weight  of  Mn.  From  this  we 
get  the  weight  of  Mn  to  which  I  c.c.  of  the  arsenite  of  sodium 
is  equivalent,  from  which  the  percentage  of  manganese  in  the 
steel  is  calculated. 

The  details  of  this  method  have  been  very  carefully  worked 
out  by  Mr.  H.  C.  Babbitt,  of  the  Wellman  Steel  Company,  who  Babbitt's 
has  used  it  for  many  years.     He  finds  that  ordinary  red  lead  is     tions. 
quite  as  effective  as  the  more  expensive  dioxide,  and  in  an  inter- 
esting series  of  experiments  he  shows  that  results   obtained  by 
filtering  off  a  portion  of  the  first  solution  obtained   by  boiling 
with  red  lead  and  titrating  are  not  accordant,  and  that  the  only 
method  of  getting  thoroughly  reliable  results  is  by  washing  out 
all  the  permanganic  acid  and  decanting  as  described  above. 

Pattinsoris  Method  (for  Spiegel  and  Ferro-manganese). 

This  method  is  based  on  the  precipitation  of  manganese  as 
MnO2,  from  a  solution    of  MnCl2,   by   hypochlorite   of  calcium 
and  carbonate  of  calcium  in  the  presence  of  ferric  chloride  (the 
presence  of  the  latter  salt  or  of  chloride  of  zinc  being  necessary 
to  prevent  the  precipitation  of  any  manganese  in  a  lower  state 
of  oxidation  than   MnO2).*     Dissolve  .5   gramme  of  spiegel  or  Details 
ferro-manganese  in  a  No.  5  beaker  in   15  c.c.  HNO3,  1.2  sp.  gr.,     method, 
evaporate  to  dryness,  and  heat  to  destroy  carbonaceous  matter. 
Redissolve  in  HC1,  and   boil  down  to   remove  HNO3,  but  not 

*  Jour.  Chem.  Soc.,  xxxv.  365. 


126  ANALYSIS   OF  IRON  AND   STEEL. 

to  dryness,  add  a  few  drops  of  HC1,  and  dilute  with  10  c.c. 
water.  Add  carbonate  of  calcium  diffused  in  water,  until  the 
solution  becomes  reddish  by  neutralization  of  the  free  acid,  then 
add  5  or  6  drops  HC1  and  100  c.c.  of  a  solution  of  bleaching 
powder  (hypochlorite  of  calcium),  made  by  treating  15  grammes 
of  the  powder  with  I  litre  of  water  and  filtering.  Now  pour  in 
about  300  c.c.  of  boiling  water,  which  will  raise  the  temperature 
of  the  solution  to  about  70°  C.,  and  add  carbonate  of  calcium, 
with  constant  stirring,  until  all  the  iron  is  precipitated.  If  the 
supernatant  fluid  has  a  pink  color,  due  to  the  formation  of  a 
little  permanganate,  add  a  few  drops  of  alcohol,  which  will  reduce 
it.  Filter  on  a  large  filter,  wash  untill  the  filtrate  is  free  from 
chlorides,  place  the  filter  and  its  contents  in  the  beaker  in  which 
the  precipitation  was  made,  and  add  100  c.c.  of  standard  solution 
of  ferrous  sulphate,  made  as  directed  on  page  1 2 1.  When  the 
precipitate  is  dissolved,  transfer  the  solution  to  the  dish,  dilute 
to  about  I  litre,  titrate  the  excess  of  ferrous  sulphate  as  directed 
on  page  121,  and  calculate  the  percentage  of  Mn  as  there 
directed. 

The  Color  Method  (for   Steel). 

This  method  was  first  suggested  by  Pichard,*  and  was  used 
essentially  in  its  present  form  by  Peters. f     It  is  now  in  very  gen- 
eral  use   in   steel-works,  and  takes   rank  with  the   color  carbon 
method   in    its    usefulness.      It    requires    one    or   more   standard 
steels    in  which  the  manganese   has  been    most  carefully  deter- 
mined  by  a  gravimetric   method.     When   a   number  of  samples 
are  to  be  tested  at  the  same  time,  as  is  usually  the  case,  a  bath 
like  the  one  shown   in   Fig.  78  is   necessary,  but  for  the  man- 
Chiondeof     ganese  color  method  it  should  contain  a  solution  of  chloride  of 
bathUm       calcium,  which  boils  at   115°  C.J      It  is,  of  course,  very  neces- 

*  Comptes-Rendus  Hebd.  des  S6ances  de  1'Acad.  des  Sciences,  Dec.  30,  1872. 
f  Chem.  News,  xxxiii.  35. 

This  latter  modification  is  due  to  Mr.  S.  A.  Ford. 


RAPID   METHODS  FOR   MANGANESE. 


127 


sary  in  a  method  of  this  kind  that  the  operations  should  always 
be  conducted  as  nearly  as  possible  under  the  same  conditions, 
and  that  the  standard  should  always  be  dissolved  at  the  same 
time  as  the  samples  to  be  tested.  Weigh  out  .2  gramme  of 
each  sample  and  of  the  standard,  and  place  them  in  8-inch  test-  method. 
tubes  properly  numbered.  Pour  into  each  test-tube  15  c.c. 
HNO3,  1.2  sp.  gr.,  cover  each  with  a  small  glass  bulb  or  very 
small  funnel,  and  stand  the  test-tubes  in  the  holes  in  the  top 
of  the  bath,  as  shown  in  the  sketch,  Fig.  78.  Heat  in  the  bath 
at  100°  C.  until  solution  is  complete.  Pour  the  contents  of  a 
test-tube  into  a  100  c.c.  tube,  wash  the  test-tube  out  with  cold 
water,  adding  it  to  the  solution  in  the  100  c.c.  tube,  and  finally 
dilute  to  the  100  c.c.  mark.  Mix  thoroughly  by  placing  the 
thumb  over  the  top  of  the  tube  and  turning  it  upside  down 
several  times.  Draw  out  10  c.c.  of  this  solution  with  a  pipette 
graduated  to  deliver  10  c.c.,  and  let  it  run  into  the  test-tube  in 
which  the  solution  was  made.  Treat  each  sample  in  this  way, 
including  the  standard.  The  tube  is  merely  washed  out  with 
water,  but  the  pipette  can  be  best  cleaned  by  drawing  it  full 
from  the  100  c.c.  tube  of  the  fresh  sample,  throwing  the  con- 
tents away,  and  -filling  it  a  second  time  to  deliver  into  the  test- 
tube.  Stand  the  test-tubes  in  the  rack  again,  add  to  each  3  c.c. 
HNO3,  1.2  sp.  gr.,  replace  the  bulbs  or  funnels,  and  stand  the 
rack  in  the  chloride  of  calcium  bath,  the  solution  in  which 
should  now  be  boiling.  When  the  solutions  in  the  test-tubes 
begin  to  boil,  add  to  each  .5  gramme  fine  peroxide  of  lead* 
and  boil  exactly  five  minutes.  The  PbO2  can  readily  be  meas- 
ured by  a  small  platinum  spoon,  made  to  hold  about  .5  gramme. 
It  is  necessary  that  the  solutions  in  the  test-tubes  should  boil, 


and  it  is  easy  to  assure  one's  self  of  this  fact  by  looking  down     solutions 
into  the  test-tubes  after  the  action   caused  by  the  addition  of 
the  PbO2  has  ceased.      Remove  the  rack  from  the  bath  at  the 


*  See  page  57. 


I2g  ANALYSIS   OF  IRON  AND   STEEL. 

expiration  of  the  five  minutes,  and  stand  it  with  the  test-tubes 
in  cold  water,  to  cool  the  solutions  and  allow  the  insoluble  lead 
salt  to  settle.  The  insoluble  matter  settles  to  the  bottom  of 
the  tube  in  a  heavy  compact  mass,  leaving  the  supernatant 
fluid  perfectly  clean.  When  this  occurs,  which  is  usually  within 
the  space  of  half  an  hour,  the  solutions  are  ready  to  be  decanted 
into  the  comparison-tubes.*  In  working  on  a  number  of  steels 
we  will  suppose  that  we  use  two  standards,  one  containing  1.2 
per  cent,  of  manganese,  the  other  .6  per  cent.  As  we  weighed 
out  .2  gramme,  diluted  the  solution  to  100  c.c.,  and  took  10 
c.c.  in  which  to  determine  manganese,  the  amount  taken  cor- 
responds to  0.02  gramme  of  the  sample;  and  if  we  dilute  the 
solutions  of  the  standards  after  decanting  into  the  comparison- 
tubes  to  24  c.c.,  one  c.c.  will  correspond  to  .05  per  cent,  in  the 
high,  and  .025  per  cent,  in  the  low,  standard.  Decant  each 
solution  in  turn  into  a  comparison-tube,  -and  dilute  it  until  it 
Comparing  has  the  exact  tint  and  depth  of  color  of  the  standard  to  which 

the  colors. 

it  most  nearly  approximates  when  first  decanted.  The  per- 
centage of  manganese  is  found  by  multiplying  the  number  of 
c.c.  to  which  the  sample  has  been  diluted  by  .05  or  .025, 
according  to  the  standard  with  which  it  has  been  compared. 
If,  however,  the  solution  of  a  sample  when  first  decanted  and 
before  dilution  should  be  lighter  in  color  than  the  lower 
standard,  the  latter  may,  after  the  other  samples  have  all  been 
finished,  be  diluted  to  30  c.c.,  when  each  c.c.  will  correspond 
to  .02  per  cent,  manganese,  or,  if  this  color  is  not  sufficiently 
light,  to  40  c.c.,  when  each  c.c.  will  correspond  to  .015  per 
cent,  manganese.  When  even  this  color  is  not  sufficiently 
light,  a  lower  standard  must  be  used  for  comparison,  or  a  larger 
amount  of  the  sample  taken  for  solution.  The  comparison  of 
the  colors  should  be  made  in  a  camera  or  box,  as  shown  in 
Fig.  8 1. 

*  See  Fig.  80. 


DETERMINATION  OF   TOTAL    CARBON.  I2g 

The  direct  rays  of  the  sun  should  not  be  allowed  to  shine 
on  the  solutions,  and  a  northern  light  for  the  comparisons  is 
preferable  to  any  other. 


DETERMINATION  OF  CARBON. 

Carbon  differs  from  all  other  elements  in  iron  and  steel  in  The  con- 

.  ditions 

that  it  is  supposed  to  exist  in  several  conditions,  and  analytical  in  which 


chemistry  supplies  the  means  of  distinguishing  between  at  least 
two  of  these  conditions.  Until  within  a  few  years  it  was  con-  and 
sidered  to  exist  in  two  forms,  as  graphite  and  as  combined  car- 
bon. To  Karsten  is  due  the  recognition  of  the  fact  that  graphite 
is  a  form  of  pure  carbon,  and  not  a  compound  of  carbon  and 
hydrogen.  It  is  always  present  as  a  mechanical  mixture,  and 
is  thus  distinguished  from  the  other  form,  which  was  supposed 
to  be  combined  chemically  with  the  iron.  Of  late  years  the 
opinion  has  been  growing  that  "  combined  carbon"  exists  in  at 
least  two  conditions  in  steel,  but  as  yet  chemical  methods  for 
separating  and  distinguishing  between  these  conditions  have 
failed,  so  far  as  quantitative  work  is  concerned.  The  analytical 
methods  here  given  are: 

The  Determination  of  Total  Carbon, 

The  Determination  of  Graphitic   Carbon,  and 

The  Determination  of  Combined  Carbon. 

DETERMINATION   OP    TOTAL    CARBON. 

We  may  divide  the  methods  for  the  determination  of  total 
carbon  in  iron  and  steel  into  the  following  classes  : 

A.  The  direct  treatment  of  the  borings  or  drillings  without 
previous  separation  of  the  iron,  including  : 

I.  Direct  combustion  in  a  current  of  oxygen  (Berzelius). 


130 


ANALYSIS  OF  IRON  AND   STEEL. 

2.  Combustion  with  chromate  of  lead  and  chlorate  of  potas- 
sium (Regnault). 

3.  Combustion  with  oxide  of  copper  in  a  current  of  oxygen 
(Kudernatsch). 

4.  Combustion  with  potassium  bisulphate  (Bourgeois). 

5.  Solution    and    oxidation    of    the    borings    in     sulphuric, 
chromic,  and   phosphoric   acids,  the   volume  of  the  CO2   being 
measured  (Wiborg,  modified). 

6.  Solution  and  oxidation  of  the  borings  as  in   5,  the  CO2 

• 
being  weighed. 

B.  Removal  of  the  iron  by  volatilization,  and  subsequent  com- 
bustion of  the  carbon,  including : 

1.  Volatilization  in  a  current  of  chlorine  (Berzelius,  Wohler). 

2.  Volatilization  in  a  current  of  hydrochloric  acid  gas  (Deville). 

C.  Solution   of  the  iron,  and  combustion  or  weighing  of  the 
residue,  including: 

1.  Solution   in    double   chloride    of  copper   and    ammonium, 
filtration,  and  weighing  or  combustion  of  the  residue  (Pearse  and 
McCreath). 

2.  Solution    in*  double    chloride    of    copper   and    potassium, 
filtration,  and  combustion  of  the  residue  in  oxygen  (Richter). 

3.  Solution    in    chloride   of  copper,    and    combustion    of  the 
residue  (Berzelius). 

4.  Solution  in  iodine  or  bromine,  and  combustion  with  chro- 
mate of  lead,  or  weighing,  of  the  residue  (Eggertz). 

5.  Solution    by  fused  chloride  of  silver,  and    combustion  of 
the  residue  (Berzelius). 

6.  Solution  of  the  iron  in  sulphate  of  copper,  filtration,  and 
combustion  of  the    residue   in    a   boat   in   a    current  of  oxygen 
(Langley). 

7.  Solution  of  the  iron  in  sulphate  of  copper,  and  oxidation 
of  the  residue  by  CrO3  and  H2SO4  (Ullgren). 

8.  Solution  in   dilute  HC1  by  the  aid  of  an  electric  current, 
and  combustion  of  the  residue  (Binks,  Weyl). 


DETERMINATION  OF   TOTAL    CARBON.  l^l 

The  most  accurate  method  is  undoubtedly  the  solution  of  the 
drillings  in  the  double  chloride  of  copper  and  potassium  and 
combustion  of  the  residue  in  oxygen  gas. 

A.  1.  Direct  Combustion  in  a  Current  of  Oxygen. 
This  method  requires  the  sample  to  be  reduced  to  a  very  fine  Necessity 

for  pow- 

state  of  subdivision,  otherwise  some  of  the  metal  in  the  centre     dermg  the 

of  the  lumps  becomes  coated  with  oxide,  and  the  carbon  in  <it 

escapes  combustion.      Weigh  out   into  a  porcelain  or  platinum 

boat,  about   3   inches  (75  mm.)  long,*    I   to   3   grammes  of  the 

sample,  and  spread  it  as  evenly  as  possible  over  the  bottom  of 

the  boat.     Place  the  boat  in  the  porcelain  tube  B,  Fig.  61,  by  Detaas 

of  the 

means  of  the  rod  C,  replace  the  stopper  P,  and  turn  on  a  current  method. 
of  oxygen  from  the  cylinder  O,  the  stopcock  R  being  open  and 
Q  closed.  The  apparatus  will  now  appear  as  in  the  cut.  The 
description  of  the  apparatus  is  given  on  page  142  et  seq.,  the 
only  difference  being  that  for  this  determination  the  U-tube  H 
and  roll  of  silver  in  the  tube  B  are  omitted.  The  precautions 
necessary  in  weighing  the  absorption  apparatus,  consisting  of  the 
bulb  I  and  tube  J,  are  also  described  fully  on  page  145.  .When 
the  tube  is  full  of  oxygen,  the  absorption  apparatus  being  weighed 
and  attached,  light  the  burners  in  the  furnace,  beginning  at  the 
forward  end,  and,  when  they  are  all  lighted,  maintain  the  tem- 
perature of  the  tube  at  a  good  red  heat  for  forty-five  minutes. 
Should  the  solution 'in  the  bulb  I  begin  to  recede,  owing  to  the 
rapid  absorption  of  oxygen  by  the  metal  in  the  boat,  increase 
the  flow  of  oxygen,  and  regulate  it  so  that  the  gas  may  never 

*I  obtained  better  results  by  using  a  platinum  boat  about  6  inches  (150  mm.) 
long  provided  with  a  cover  of  platinum-foil,  through  which  a  semicircular  cut  was 
made  about  every  y2  inch  (12  mm.).  On  raising  these  pieces  to  an  angle  of  45° 
they  formed  a  series  of  little  wings,  which  directed  the  current  of  gas  flowing  along 
the  upper  part  of  the  tube  down  into  the  boat.  It  is  difficult  to  get  a  sufficiently 
high  temperature  in  a  porcelain  tube,  but  the  results  obtained  in  a  platinum  tube  were 
very  satisfactory.  (See  Jour,  of  Anal,  and  App.  Chem.,  1891,  p.  125.) 


l$2  ANALYSIS   OF  IRON  AND   STEEL, 

pass  through  the  bulb  I  more  rapidly  than  3  or  4  bubbles  in  a 
second.  At  the  expiration  of  the  forty-five  minutes,  shut  off  the 
current  of  oxygen  at  O,  close  the  stopcock  R,  open  Q,  and  start 
the  current  of  air  by  opening  T  gradually,  so  that  the  water  may 
flow  into  the  lower  bottle  F.  Turn  down  the  lights  in  the  fur- 
nace slowly,  to  avoid  cracking  the  tube,  finally  turn  them  out, 
and  allow  the  current  of  air  to  run  through  the  apparatus  until 
the  oxygen  is  expelled.  This  will  usually  be  accomplished  by 
running  out  half  the  water  in  the  bottle  F.  Close  the  stopcock 
T,  remove  the  absorption  apparatus,  and  weigh  it.  The  increase 
of  weight  will  be  CO2,  due  to  the  carbon  in  the  sample,  and  it 
contains  27.27  per  cent,  carbon. 

2.   Combustion  with  Chromate  of  Lead  and  Chlorate  of 

Potassium. 

preparation          This  method,  like  the  preceding  one,  requires  the  sample  to 

combus-     be  very  finely  powdered.      Take  a  piece  of  combustion-tubing 

bes'  about    32    inches    (800   mm.)  long,    */2    inch  (12    mm.)    internal 

diameter,  and  ^  inch  (1.5   mm.)  thick   in  the  walls;    heat  it  in 

the  middle  by  means  of  a  blast-lamp  until   it  softens,  draw  the 

ends  apart  slightly,  and  then,  keeping  the  ends  parallel,  draw  it 

out,  as  shown  in   Fig.  55.      Allow  it  to  cool,  scratch  it  in  the 

middle  with  a  file,  and 
FIG.  55. 

break  it.      This  gives 

two  tubes  each  about 
1 6   inches    (400   mm.) 
Fuse  the  laree 


ends  slightly  so  as  to  round  the  sharp  edges,  but  avoid  con- 
tracting the  tube.  Wash  the  tubes  thoroughly,  using  a  rod 
with  a  piece  of  dark-colored  silk  or  linen  on  the  end ;  then  if 
any  lint  remains  on  the  inside  of  the  tube  it  can  be  easily 
seen.  Dry  the  tubes  by  heating  them  carefully  and  drawing  air 
through  them,  then  fuse  the  small  ends  and  cork  the  large  ends 
to  keep  out  the  dust.  Weigh  out  I  to  3  grammes  (i  gramme 


DETERMINATION  OF  TOTAL    CARBON. 

of  pig-iron,  spiegel,  or  ferro-manganese,  3  grammes  of  steel)  of 
the  sample,  and  grind  it  thoroughly  in  a  small  mortar  with  15 
times  its  weight  of  fused  and  powdered  chromate  of  lead  and 
\y2  times  its  weight  of  fused  and  powdered  chlorate  of  potas- 
sium or  bichromate  of  potassium.  Bichromate  of  potassium  is 
to  be  preferred,  as  a  little  chlorine  is  sometimes  given  off  by 
chlorate  of  potassium  when  used  in  this  manner.  Place  the  Details 
combustion-tube  in  a  stand,  as  shown  in  Fig.  56,  and  push 


133 


FIG.  56. 


down  into  the  end,  with  a  clean  glass 
rod,  a  little  ignited  asbestos.  The 
asbestos  should  not  be  tightly  packed, 
as  it  will  prevent  the  air  from  passing 
in  freely  at  the  end  of  the  operation. 
Place  a  small,  dry,  perfectly  clean 
funnel  in  the  end  of  the  tube,  and 
pour  through  it  enough  of  the  pure 
powdered  chromate  of  lead  to  fill  the 
tube  for  about  one  inch  of  its  length. 
Hold  the  mortar  under  the  funnel  so 
that  anything  that  falls  from  it  may 
go  into  the  mortar,  and  charge  the  mixture  into  the  tube  by 
means  of  a  small  platinum  spatula.  Clean  out  the  mortar  by 
grinding  in  it  two  or  three  successive  small  portions  of  chromate 
of  lead,  charging  each  into  the  tube  through  the  funnel.  Re- 
move the  funnel,  cork  the  tube,  and,  holding  it  in  a  horizontal 
position  with  the  tail  up,  tap  it  gently  to  get  a  clear  space  for 
the  passage  of  the  gas  from  one  end  of  the  tube  to  the  other. 
Place  the  tube  in  the  combustion-furnace,  remove  the  cork,  and 
insert  in  its  place  a  smooth  velvet  cork,  through  the  centre  of 
which  passes  one  end  of  a  Marchand  U-tube.  The  half  of  this 
tube  nearest  the  combustion-tube  contains  anhydrous  sulphate 
of  copper,*  and  the  other  -half  granulated  dried  chloride  of 


*  See  page  53. 


134  ANALYSIS   OF  IRON  AND   STEEL. 

calcium,  the  two  reagents  being  separated  by  a  small  plug  of 
fibrous  asbestos  loosely  packed.  Weigh,  and  attach  the  absorp- 
tion apparatus  and  safety-tube.  Apply  suction  at  the  end  of 
the  rubber  tube  on  the  forward  end  of  the  safety-tube,  and 
draw  a  few  bubbles  of  air  through  the  potash-bulb.  Allow  the 
liquid  to  recede  gradually ;  if  it  maintains  its  level  in  the  bulb 
for  a  few  minutes,  the  joints  of  the  apparatus  may  be  con- 
sidered tight,  but  if  it  gradually  falls,  it  is  proof  that  there  is  a 
Testing  the  leak,  and  the  joints  must  all  be  tightened.  If,  after  pushing 
of  the  con-  the  cork  as  far  as  possible  into  the  end  of  the  combustion- 
tube  and  binding  all  the  rubber  connections,  another  trial  still 
shows  a  leak,  a  fresh  cork  must  be  substituted.  When  the 
joints  are  all  tight,  light  the  burner  at  the  forward  end  of  the 
tube,  and  each  burner  successively  as  the  flow  of  gas  slackens, 
bringing  the  tube  over  each  burner  to  a  red  heat  before  lighting 
the  next  one.  Maintain  the  whole  length  of  the  tube  up  to  the 
asbestos  at  a  good  red  heat  until  the  flow  of  gas  entirely  ceases. 
Then  pass  a  piece  of  rubber  tubing  attached  to  a  purifying 
apparatus  well  over  the  tail  of  the  tube,  which  should  be  cool 
enough  to  be  handled,  break  the  point  of  the  tail  inside  the 
tubing,  lower  the  lights  a  little,  and,  by  means  of  the  aspirator- 

FIG.  57. 


bottles,  force  about  I  litre  of  air  through  the  apparatus.  It 
will  now  appear  as  in  Fig.  57.  Turn  out  the  lights,  and  de- 
tach and  weigh  the  absorption  apparatus,  with  the  precautions 


DETERMINATION  OF  TOTAL    CARBON.  l^ 

mentioned  on  page  144.  The  increase  of  weight  will  be  the 
CO2  due  to  the  carbon  in  the  sample.  This  contains  27.27  per 
cent,  carbon. 

3.  Combustion  with  Oxide  of  Copper  in  a  Current  of 

Oxygen. 

Prepare  the  combustion-tube  as  directed  in  the  last  method,  Details 

of  the 

and  pour  on  the  asbestos  in  the  end  of  the  tube  enough  oxide     method. 
of  copper  to  fill  the  tube  to  the  height  of  about  an  inch  (25  mm.). 
Mix   the   weighed   sample,   I   to   3   grammes   in  a  fine  state  of 
division,  with   at   least  20  times    its  weight   of  finely-powdered 
pure  oxide  of  copper,  charge  it  into  the  tube  as  directed  on  page 
133,  rinse  out  the  mortar  with  a  little  more  of  the  same  material, 
and  finally  fill  the  tube  to  within  an  inch  (25  mm.)  of  the  end 
with  granulated  oxide  of  copper.     Make  the  combustion  exactly 
as  directed  in  the  last  method,  page  1 34.     If  the  combustion  is  Using  a 
to  be  made  in  a  current  of  oxygen,  which  is  much  the  best  plan,     oxygen, 
instead  of  drawing  the  combustion-tube  out  to  a  point  and  sealing 
it,  it  may  be  drawn  out  straight,  as  shown  in  Fig.  58.     In  this 
FIG.  58.  case,  attach  to  the  drawn-out  end 

U  ^-^^   when  the  tube  is  in  the  furnace  a 

purifying  apparatus  for  oxygen  and  air,  as  shown  in  Fig.  61,  and 
conduct  the  operation  as  directed  on  page  131. 

4.  Combustion  with  Potassium  Bisulphate. 

Certain  classes  of  special  material,  such  as  ferro-chrome, 
cannot  be  decomposed  by  any  solution,  nor  can  the  carbon  be 
determined  by  direct  combustion  in  oxygen. 

The  only  known   method  is  by  fusion  with  potassium  bisul- 

phate.  Method  for 

Weigh  I  gramme  of  the  finely-powdered  sample  into  a 
porcelain  boat  about  150  mm.  long,  25  mm.  high,  and  30  mm. 
wide,  and  mix  intimately  with  30  to  40  grammes  of  fused 
powdered  potassium  bisulphate.  Place  the  boat  in  a  porcelain 


136  ANALYSIS   OF  IRON  AND   STEEL. 

tube  arranged  as  in  Fig.  61.  Connect  the  tube  at  the  forward 
end  with  a  flask  containing  a  mixture  of  sulphuric  and  chromic 
acids,  which  can  be  heated.  Connect  with  this  a  U-tube  con- 
taining pumice  saturated  with  chromic  acid,  then  U-tubes,  G 
and  H,  Fig.  61,  filled  as  described  on  page  144.  Attach  the 
absorption  apparatus  and  heat  the  forward  end  of  the  porcelain 
tube  containing  the  oxide  of  copper,  and  warm  the  flask  con- 
taining the  sulphuric  and  chromic  acids.  Heat  the  tube  where 
the  boat  is  very  gently  for  two  hours  and  gradually  raise  the  heat 
to  dull  redness  for  half  an  hour,  continuing  the  passage  of  the 
oxygen.  Shut  off  the  oxygen  and  pass  the  air  for  20  minutes. 

Weigh  the  absorption  apparatus  in  the  usual  way.  The 
liberated  sulphurous  acid  is  oxidized  by  the  oxide  of  copper  or 
the  chromic  acid,  and  only  the  carbonic  acid  finds  its  way  into 
the  absorption  apparatus. 

5.  Solution  and  Oxidation  of  the  Borings  in  Sulphuric, 

Chromic,  and  Phosphoric  Acids,  the  Volume  of 

the  CO2  being1  measured. 

The  method  given  below  for  the  determination  of  carbon  in 
steel  is  generally  used  in  the  steel  works  laboratories  in  the 
eastern  part  of  France,  and  I  am  indebted  for  the  details  to 
Monsieur  H.  A.  Brustlein  of  Jacob  Holtzer  &  Cie,  of  Unieux, 
at  whose  works  and  at  those  of  the  Acieries  de  la  Marine  at 
Saint  Chamond  the  various  improvements  in  the  method  have 
been  worked  out. 

The  method  was  first  suggested  by  Wiborg,*  but  was  very 
imperfect  in  its  original  form.  The  greatest  improvement  was 
suggested  by  Monsieur  de  Nolly,  of  the  Laboratory  of  the 
Acieries  de  la  Marine  at  Saint  Chamond,  and  consists  in  the 
addition  of  phosphoric  acid  to  the  oxidizing  mixture,  by  which 
the  iron  is  much  more  rapidly  dissolved  and  the  use  of  a  con- 

*  Stahl  und  Ei<en,  1887,  p.  465. 


DETERMINATION  OF   TOTAL    CARBON.  l^ 

siderable  amount  of  chromic  acid  is  rendered  possible  without 
the  evolution  of  a  large  volume  of  oxygen  gas.  M.  Benazet 
and  M.  Florence,  of  Unieux,  substituted  mercury  for  water  in 
the  original  method. 

The  solutions  employed  are: 

1.  A  saturated  solution  of  chemically  pure  cupric  sulphate. 

2.  An  aqueous  solution  of  chromic  acid  (i  gramme  chromic 
acid  to   i   c.c.  water). 

3.  A   mixture   of    sulphuric,    phosphoric,   and    chromic   acid 
made  up  as  follows : 

Solution  of  chromic  acid  (Sol.  No.  2) 35  c.c. 

Water 190   "  Solutions 

Concentrated  sulphuric  acid 75°  "  required 

Phosphoric  acid  1.4  sp.  gr 340   " 

In  preparing  solution  No.  2,  add  a  few  c.c.  of  sulphuric  acid 
and  heat  to  boiling  to  destroy  any  organic  matter  that  may  be 
present. 

In  preparing  solution  No.  3,  heat  it  to  boiling  also  for  the 
same  purpose. 

The  apparatus  as  shown  in  the  sketch  consists  of  a  round- 
bottom  flask,  A-  of  250  c.c.  capacity,  with  a  long  neck.  The 
flask  is  closed  with  a  rubber  stopper  with  two  holes,  in  one  of 
which  is  fitted  the  glass  stopper  funnel  B  and  in  the  other  the 
tube  C  enclosed  in  the  condenser  D,  through  which  a  stream  of 
water  runs  during  the  operation.  The  tube  C  is  connected  with 
one  tube,  E,  of  a  three-way  stopcock,  a,  from  which  the  second 
tube,  F9  opens  into  the  air  and  the  third,  G,  connects  with  the 
tube  H  of  the  three-way  stopcock  b.  The  second  tube,  Jt  from 
this  stopcock  is  fused  to  the  burette  K.  which  is  enclosed  in  the  Description 

of  the 

tube  L  containing  water.     The  lower  end  of  the  burette  connects     apparatus, 
with  a  tube,  M,  of  small  interior  diameter,  which  serves  as  a  level 
tube  and  is  in  the  form  of  a  T ;  it  is  connected  with  the  mercury 
reservoir  N,  which  is  raised  and  lowered  by  the  arrangement  0. 
The  third  tube  of  the  stopcock  b  connects  with  the  tube  P  of 


138 


ANAL  YSIS   OF  IRON  AND   STEEL. 

the  stopcock  c,  the  second  tube,  Q,  of  the  stopcock  c  connects 
with  the  manometer  R,  and  the  third  tube,  S,  with  the  pipette 
T,  which  runs  into  the  bottle  U.  The  tubes  of  the  stopcocks  b 

FIG.  59- 


and  c,  the  manometer  tube  R,  the  level  tube  M,  and  the  tubes  of 
the  pipette  T  are  capillaries.  The  manometer  tube  R  contains 
water,  and  serves  to  accurately  adjust  the  levels  when  taking  the 


DETERMINATION  OF   TOTAL    CARBON. 

reading  of  the  burette  K.  When  the  manometer  is  shut  off 
from  the  burette  the  approximate  level  is  ascertained  by  means 
of  the  level  tube  M.  The  tube  F  of  the  stopcock  a  is  used  only 
in  exceptional  cases :  First,  when  the  evolution  of  gas  is  insuffi- 
cient to  carry  the  mercury  far  enough  down  the  burette  K,  in 
which  case  air  is  drawn  through  it  into  the  burette ;  and  secondly, 
when  the  evolution  of  gas  is  so  great  that  it  is  necessary  to  make 
two  absorptions  in  the  pipette  T,  in  which  case  the  residue  from 
the  first  absorption  is  discharged  through  the  tube  F.  The 
pipette  T  contains  a  solution  of  potassium  hydroxide  of  1.27 
sp.  gr.,  it  is  of  about  400  c.c.  capacity.  The  bottle  U  is  of  about 
one  litre  capacity.  The  water  in  the  containing  tube  L  serves  to 
keep  the  gas  in  the  burette  at  the  ordinary  temperature  of  the 
laboratory.  It  should  be  protected  from  the  heat  of  the  burner 
and  flask  by  a  screen. 

The  operation  is  conducted  as  follows : 

Connect  the  pipette  T,  by  means  of  the  stopcocks  b  and  c, 

with  the  burette  K  and,  by  lowering  the  mercury  reservoir,  fill  The  opera- 
tion. 

the  pipette  with  the  potassium  hydroxide  solution,  close  the  stop- 
cock c,  fill  the  burette  K  with  mercury,  and  close  the  stopcock  b. 
Weigh  i  gramme  of  drillings  into  the  flask  A,  attach  it  to  the 
apparatus,  start  the  water  through  the  condenser  D,  and  con- 
nect the  flask  with  the  burette  K  by  means  of  the  stopcock  a. 
Pour  fifteen  c.c.  of  the  cupric  sulphate  solution  No.  I  into  the 
funnel  tube  B,  and  let  it  flow  into  the  flask.  Allow  it  to  act 
long  enough  to  form  a  superficial  deposit  of  copper  on  the 
drillings  (one  or  two  minutes  is  sufficient),  then  add,-  through 
the  funnel  tube,  fifteen  c.c.  of  solution  No.  2  and  135  c.c.  of  solu- 
tion No.  3.  Heat  the  solution  in  the  flask  and  raise  it  slowly  to 
the  boiling-point.  By  means  of  the  reservoir,  keep  the  mercury 
in  the  burette  and  in  the  tube  M  nearly  level.  The  water  con- 
densed in  the  tube  C  drops  back  into  the  flask  and  keeps  the 
liquid  of  the  same  density,  while  the  properly  cooled  gases  pass 
into  the  burette. 


140 


ANAL  YSIS   OF  IRON  AND   STEEL. 


Calculation 
of  the 
results. 


Description 
of  the 
apparatus , 


Allow  the  flask  A  to  cool  for  about  five  minutes,  and  then 
run  into  it,  through  the  funnel  tube  B,  enough  water  to  fill  the 
flask  and  the  tube  to  the  stopcock  a,  thus  forcing  all  the  gas 
into  the  burette.  Close  the  stopcock  a  and  connect  the  burette, 
by  means  of  the  stopcocks  b  and  c,  with  the  manometer  R,  adjust 
the  levels  accurately,  and  take  the  reading  of  the  burette.  Then 
by  means  of  the  stopcock  c  connect  the  burette  with  the  pipette 
T  and,  by  raising  and  lowering  the  reservoir  Nt  pass  the  gas 
several  times  back  and  forth  to  cause  the  potassium  hydroxide 
to  absorb  all  the  carbon  dioxide.  Finally  connect  the  burette 
with  the  manometer  tube  R,  adjust  the  levels,  and  take  the 
reading  of  the  burette. 

The  burette  K  should  contain  a  few  drops  of  water  to  insure 
the  saturation  of  the  gases  with  aqueous  vapor.  The  difference 
between  the  two  readings  is  the  volume  of  the  carbon  dioxide. 
Observe  the  readings  of  the  thermometer  and  barometer  and 
reduce  the  volume  of  the  carbon  dioxide  to  that  which  it  would 
occupy  in  the  dry  state  at  o°  C.  and  760  mm.  pressure.  (Table  V.) 

Multiply  the  volume  of  the  gas  so  obtained  by  0.0019663,  and 
the  result  is  the  weight  of  the  carbon  dioxide  in  grammes. 

6.    Solution  and  Oxidation  of  the  Borings  as  in  5,  the  CO2 

being  weighed. 

Fig.  60  shows  the  details  of  the  apparatus  for  carrying  out 
this  method.  M  is  the  U-tube  for  purifying  the  air.  It  contains 
fused  caustic  potassa.  A  is  the  flask  for  oxidizing  and  dissolving 
the  sample.  The  piece  of  glass  tubing  TV  bent  at  a  right  angle 
is  drawn  out  slightly  at  the  lower  end,  over  which  a  piece  of 
soft  gum  tubing  is  fitted,  forming  a  stopper,  which  fits  tightly  in 
the  top  of  the  bulb-tube  when  air  is  forced  through  the  appa- 
ratus. B  is  a  bulb-tube  for  introducing  the  reagents.  The  lower 
end  is  drawn  out  so  that  the  orifice  is  quite  small.  0  is  a  con- 
denser, P  contains  anhydrous  cupric  sulphate,  Q  granular  chloride 
of  calcium,  and  the  small  bulb  of  P  and  Q  contains  cotton-wool. 


DETERMINATION  OF  TOTAL    CARBON. 


141 


142  ANAL  YSIS   OF  IRON  AND   STEEL. 

The  Liebig  bulb  and  the  tube  R  form  the  absorption  apparatus, 
and  6*  the  safety-tube.  Conduct  the  operation  as  described  on 
page  139,  pass  two  litres  of  air  through  and  weigh  the  absorp- 
tion apparatus  as  described  on  page  146. 

B.  1.  Volatilization  of  the  Iron  in  a  Current  of  Chlorine,  and 
Subsequent  Combustion  of  the  Carbon. 

Weigh  out  i  gramme  of  pig-iron  or  3  grammes  of  steel  into 

a  porcelain  boat  about  3  inches  (75  mm.)  long,  and  treat  it  ex- 

*actly  as  described  on  page  73  et  seq.     The  boat  when  withdrawn 

from  the  tube  contains  the  carbon,  slag,  and  oxides,  and  nearly 

all    of   the   non-volatile    chlorides,   such   as   MnCl2.      When   the 

sample  contains   much    manganese,   it  is   necessary  to  treat  the 

residue  in  the  boat  with  cold  water,  filter  it  on  a  small  plug  of 

ignited  asbestos,  return  it  to  the  boat,  and  dry  it  before  burning 

This  method  it  off.     As  this  adds  very  considerably  to  the  time  required  for 

not  suit- 
able for       the   determination,   it  is   best  to    adopt    some   other    method   for 

Inchferro-    the  determination   of  carbon    in    such    materials    as   spiegel    and 
ferro-manganese.       Introduce  the   boat    into   the   tube   B   of  the 
Description    apparatus,    Fig.    61.      This    apparatus    consists    of   a    ten-burner 
combus-      combustion-furnace  A,  through  which   runs    the   porcelain   tube 
ratus*1*1      B.     This  tube  is  about  25    inches  (625    mm.)  long,  and  ^  inch 
(18    mm.)   internal    diameter.       It   projects   6   inches    (150   mm.) 
outside  the  furnace  at  each   end,   and  the  sheet-iron   screens  L 
prevent    the    heat   from    reaching   the    stoppers    P    and    S.     The 
Preparation    tube  is  filled  for  a  length  of  6  inches  (150  mm.),  or  from  about 
ideofcop-  the  middle  of  the  tube  to  the    forward  end  of  the  furnace,  with 
oxide  of  copper,  which    is   best    made   by   rolling   up   tightly  a 
piece  of  coarse  copper   gauze  6  inches  (150  mm.)  long    until  it 
makes  a  roll  nearly  filling  the  bore  of  the  tube,  and  heating  it 
Ron  of         for  an  hour  in  a  current  of  oxygen.      A  piece   of  thin   sheet- 
silver  4  inches   long,  and  forming  a   roll   completely  filling  the 
bore  of  the  tube,  is  placed  just  in  front  of  the  oxide  of  copper: 
it  serves  to  absorb  any  chlorine  given   off  during  the  combus- 


DETERMINATION  OF   TOTAL    CARBON. 


ANALYSIS   OF  IRON  AND   STEEL. 

tion.*      A  roll  of  copper  gauze   2   inches   long,  with   a   loop   in 
one  end,  thoroughly  oxidized,  is   pushed   in  after  the  boat   con- 
taining   the    carbon.      The    cylinder    O    contains    oxygen    under 
Air.  pressure.      The    bottles    F,    F    serve   to    force    air    through    the 

apparatus  to  replace  the  oxygen  at  the  end  of  the  operation. 
The  stopcock  T  serves  to  regulate  the  flow  of  water,  and  con- 
sequently of  air.  When  all  the  water  has  run  from  the  upper 
into  the  lower  bottle,  it  is  siphoned  out  of  the  latter  and  re- 
turned to  the  former. 

Purifying  The  purifying  apparatus  M  and  N,  for  oxygen  and  air  respec- 

for oxygen  tively,  consist  of  Liebig  potash-bulbs  filled  with  caustic  potassa, 
1.27  sp.  gr.,  and  U-tubes,  the  sides  next  the  potash-bulbs  filled 
with   dry  pumice,  and  the  other  sides  with  chloride  of  calcium. 
The  glass  stopcocks  Q  and  R  shut  off  the  purifying  apparatus  on 
their  respective  sides  when  the  oxygen  or  air  is  passing  through 
the  other  set.      The  T-tube   D   connects  the  two  sets  of  appa- 
ratus, the  third   limb  passing  through  the  glass  in  the  side   of 
the  hood,  and  connecting  by  means  of  the  bent-glass  tubes  with 
the   rubber  stopper   P,  which  fits   in   the  porcelain  tube  B.     All 
Danger  of      the  connections   are   made  with   glass   tubes  joined  together  by 
her  tubes,    rubber  tubing,  the  ends  of  the  glass  tubing  being  brought  close 
together  inside  the  rubber.     This  is  to  avoid  carrying  the  oxygen 
or   air  through   rubber   tubing,  which   gives   off  volatile    hydro- 
Drying  and    carbons.     The  Marchand  U-tube  G  contains  anhydrous  sulphate 
apparatus    °f  copper  to  absorb  any  HC1  which  may  be  evolved  during  the 
Asbestos*      combustion.     It  is  joined  to  the  tube  B  by  a  rubber  stopper  or 
stopper.      kv  an  asbestos  stopper,f  made  by  pressing  wet  fibrous  asbestos 
into  a  mould  of  the  proper  shape.     When  sufficient  pressure  is 
applied  in  making  the  stopper  it  becomes  very  hard.     When  dry 
it  can  be  bored  easily,  and  makes  an  excellent  stopper  for  this 
purpose.     The  U-tube  H  contains   granulated  dried   chloride  of 

*  This   roll  of  silver   must   be  occasionally  removed   and  ignited  in  a  current 
of  hydrogen  to  remove  the  chlorine. 

f  J.  F.  White,  Amer.  Chem.  Jour.,  iii.  151. 


DETERMINATION  OF   TOTAL    CARBON.  l^ 

calcium.*  The  absorption  apparatus  consists  of  the  Liebig  bulb  Absorption 
I  and  the  drying-tube  J.  I  contains  caustic  potash,  1.27  sp.  gr. 
It  is  filled  by  attaching  a  short  piece  of  rubber  tubing  to  one 
end  and  applying  suction  to  it,  the  other  end  being  immersed 
in  the  potassa  solution,  which  has  been  poured  into  a  capsule. 
The  end  must  be  wiped  dry  with  a  little  filter-paper,  and  the 
inside  of  the  tube  dried  in  the  same  way.  When  filled,  the  bulb 
should  contain  the  solution  as  shown  in  Fig.  62.  When  attached 
to  the  apparatus,  the  gas  passes  first  into  F 

the  large  bulb,  and,  the  bulbs  being  in- 
clined, the  gas  bubbles  through  the  solu- 
tion in  the  three  bottom  bulbs.  It  is 
fitted  with  a  loop  of  platinum  wire,  as 
shown  in  Fig.  62.  The  drying-tube  J 
contains  dried  chloride  of  calcium.  The 
small  bulb  a,  Fig.  61,  contains  a  plug  of 
cotton-wool,  and  another  plug  of  the  same 
material  is  inserted  after  the  chloride  of 
calcium  at  b.  K  is  a  safety-guard  tube,  Safety-guard 

to  prevent  moisture  from  getting  into  the  tube  J  during  the  com-  tube' 
bustion.  The  short  rubber  tube  V  is  used  to  draw  a  little  air 
through  to  test  the  tightness  of  the  joints.  All  the  stoppers  in 
the  various  U-tubes  and  drying-tubes  are  of  rubber.  The  copper 
rod  C  is  used  to  introduce  the  boats,  etc.,  into  the  tube  B,  run- 
ning the  crooked  end  through  the  hole  W  in  the  glass  side  of  the 
hood.  When  not  attached  to  the  apparatus,  the  ends  of  the 
potash-bulb  I  and  drying-tube  J  are  closed  by  little  caps  of  rubber 
tubing  f  (Fig.  62)  made  like  the  tips  for  "  policemen."  When  on 
the  balance,  however,  they  should  be  closed  with  short  pieces 
of  rubber  tubing  containing  bits  of  capillary  glass  tubing,  as 
shown  in  Fig.  63.  The  forward  end  of  the  drying-tube  is  closed 
in  the  same  way.  These  openings  are  too  small  to  allow  the 


*  See  page  52.  f  See  page  31. 

10 


ANALYSIS   OF  IRON  AND   STEEL. 

condition  of  the  atmosphere  to  affect  the  weight  of  the  bulbs  by 
loss  or  gain  of  moisture,  but  they  serve  to  equalize  the  pressure 
FlG  6-  and  make  it  unnecessary  to 

reopen  the  balance-case  until 
the  bulbs  are  weighed. 

Precauti°ns  /A^r^x  Jt   is    very  necessary   in 

m  weigh-  7Hi      V^\ 

insthe  ///If          )  filling    the    potash-bulb    to 

absorp-  W  V  / 

avoid    getting    any    of    the 
solution  on   the   outside    of 


the  bulb,  and  it  is  well  to 
see  that  both  the  bulb-tube 
and  the  drying-tube  are  per- 
fectly clean.  Wipe  off  the 
potash-bulb  and  drying-tube 
with  a  piece  of  linen,  not 
silk  (a  clean  linen  handker- 
chief that  does  not  leave  lint  on  the  glass  is  very  good  for  this 
purpose),  and  place  them  on  the  balance. 

The  little  wire  stand  shown  in  Fig.  63  is  very  convenient  for 
holding  the  absorption  apparatus  in  the  balance,  as  it  brings  all 
the  weight  on  the  pan  instead  of  putting  the  greater  part  on  the 
beam  alone,  as  is  the  case  when  the  potash-bulbs  are  suspended 
from  the  hook  on  the  end  of  the  beam.  The  latter  arrangement 
puts  more  weight  on  one  pan  than  on  the  other,  thus  throwing 
the  needle  out  of  the  vertical.  Allow  them  to  remain  about 
thirty  minutes  to  get  the  exact  temperature  of  the  balance,  and 
Details  of  weigh.  Attach  the  absorption  apparatus  as  shown  in  the  sketch, 

the  com- 
bustion. Fig.  6 1,  insert  the  boat  in  the  tube  by  means  of  the  rod  C,  push- 
ing it  up  against  the  oxide  of  copper,  insert  the  short  roll  of 
oxidized  gauze  as  far  as  the  inside  of  the  screen  L,  and  close  the 
tube  with  the  stopper  P.  Shut  the  stopcocks  R  and  Q,  and,  by 
applying  suction  at  V,  draw  a  few  bubbles  through  the  potash- 
bulb  I.  When  the  liquid  recedes  in  the  potash-bulb,  it  should 
keep  its  level  for  a  few  minutes ;  if  it  does  not,  there  is  a  leak  in 


DETERMINATION  OF   TOTAL    CARBON.  147 

some  of  the  connections,  which  must  be  discovered  and  stopped 
before  proceeding  with  the  combustion.  When  everything  is 
tight,  open  R  and  start  a  slow  current  of  oxygen  through  the 
apparatus.  Light  the  two  forward  burners  of  the  furnace,  turning 
them  low  to  heat  the  oxidized  copper  gauze,  raise  the  heat  grad- 
ually until  the  tube  appears  red,  and  then  light  the  last  burner 
to  heat  the  short  roll  of  oxidized  copper  gauze.  As  soon  as 
this  end  of  the  tube  is  hot,  light  the  third  burner  from  the 
forward  end,  and  a  few  minutes  afterwards  the  fourth  burner, 
which  is  directly  under  the  forward  end  of  the  boat.  Light 
each  burner  in  succession  from  this  one  until  all  are  lighted 
and  turned  high  enough  to  heat  the  tube  red-hot.  Allow  them 
to  burn  for  fifteen  minutes,  then  shut  off  the  oxygen,  close  R, 
open  Q,  and  by  means  of  the  stopcock  T  start  a  current  of 
air  through  the  apparatus.  By  means  of  the  gas-cock  X  lower 
all  the  lights  of  the  furnace  together  very  slowly,  to  avoid 
cracking  the  tube,  and  finally  turn  them  out.  About  I  litre 
of  air  should  run  through  at  the  rate  of  about  3  bubbles  a 
second;  this  will  about  half  empty  the  upper  bottle  L.  Close 
T  and  Q,  detach  the  absorption  apparatus,  close  the  ends  of  I 
and  J  with  the  little  rubber  caps,  and,  after  wiping  the  bulb  and 
tube  gently  with  the  linen  handkerchief  to  remove  any  moisture 
caused  by  the  handling,  place  them  on  the  balance.  Weigh 
with  the  same  precautions  as  before  ;  the  increase  in  weight  is 
CO2,  which  contains  27.27  per  cent,  carbon.  When  several  com-  when 
bustions  are  to  be  made  in  succession,  as  soon  as  the  absorption  "number 
apparatus  is  detached  as  directed  above,  remove  the  boat  from 
the  tube,  replace  it  with  another  containing  a  second  sample, 
attach  a  second  absorption  apparatus  which  has  just  been 
weighed,  and  proceed  with  the  combustion.  While  the  second 
combustion  is  in  progress,  the  first  absorption  apparatus  may  be 
weighed,  and  the  weight  then  obtained  can  be  used  for  the  first 


weight  of  the  absorption  apparatus  for  a  third  combustion.     Be-     ins  KHO 

solution 

fore  the   absorption    apparatus   shall    have  increased   .5   gramme     frequently. 
in  weight  from  the  original  weighing,  the  potash-bulb  must  be 


148 

Condition 


when  Lt 

in  use. 


Tube  to  be 
before 


obtained 

in  very 

damp, 
weather, 


Apparatus 


ANAL  YS2S   OF  IRON  AND   STEEL. 

emptied  and  refilled  with  a  fresh  solution.  When  the  final  com- 
bustion for  the  day  is  finished,  place  a  piece  of  glass  rod  in  the 
open  end  of  the  connection  of  H,  remove  the  boat  from  the 
tube  B,  replace  the  short  roll  of  oxidized  copper  gauze  in  the 
tube,  insert  the  stopper  P,  but  not  tightly,  open  R  and  Q,  and 
loosen  the  stopper  in  the  bottle  F.  Place  pieces  of  glass  rod 
in  the  ends  of  the  safety-tube  K,  to  prevent  access  of  moisture. 
Whenever  the  apparatus  has  been  out  of  use  for  a  day,  before 
making  a  combustion  or  set  of  combustions  remove  the  piece 
of  glass  rod  from  the  forward  end  of  the  U-tube  H,  insert  in  its 
place  a  piece  of  glass  tubing  drawn  out  at  the  forward  end  to  a 
small  orifice,  start  a  current  of  oxygen  through  the  apparatus,  light 
the  burners  in  the  furnace,  raising  the  heat  very  gradually,  keep 
the  tube  at  a  red  heat  fifteen  minutes,  turn  off  the  oxygen,  start 
the  air,  lower  the  burners  gradually,  and  pass  a  litre  of  air  through 
the  apparatus.  It  will  then  be  ready  for  the  combustion.  In 
very  damp  weather  it  is  almost  impossible  to  get  good  results,  the 
condensation  of  moisture  on  the  absorption  apparatus  rendering 
the  weighing  extremely  difficult  even  when  the  utmost  care  is  used. 

2.     Volatilization  of  the    Iron   in  a  Current  of  Hydrochloric 
Acid  Gas,  and  Subsequent  Combustion  of  the  Carbon. 

The  process  is  exactly  the  same  in  this  method  as  in  that  just 
described,  a  current  of  hydrochloric  acid  gas  being  substituted 
for  one  of  chlorine.  The  apparatus  for  generating  this  gas  is  the 
same  as  the  one  used  for  chlorine,  common  rock-salt  in  pieces 
about  as  large  as  a  filbert  being  substituted  for  binoxide  of  man- 
ganese, and  sulphuric  acid,  diluted  with  two-thirds  its  bulk  of 
water,  for  hydrochloric  acid. 

C.  1.  Solution  in  Double  Chloride  of  Copper  and  Ammonium,* 
Filtration,  and  "Weighing  or  Combustion  of  the  Residue. 

Weigh  i  gramme  of  pig-iron,  spiegel,  or  ferro-manganese  into 
a  No.  2  Griffin's  beaker,  and  add  100  c.c.  of  saturated  solution  of 


The  potassium  salt  is  now  in  general  use  and  is  preferred  by  most  chemists. 


DETERMINATION  OF   TOTAL    CARBON. 


149 


the  double  chloride  of  copper  and  ammonium*  and  7.5  c.c.  HC1. 
For  steel  or  puddled  iron,  weigh  3  grammes  f  into  a  No.  3  beaker, 
and  add  200  c.c.  of  the  double  chloride  of  copper  and  ammonium 
solution  and  15  c.c.  strong  HCL  Stir  the  solution  constantly  with 
a  glass  'rod  for  some  minutes  at  the  ordinary  temperature.  The 
more  it  is  stirred  the  more  rapid  will  be  the  solution  of  the  iron  Solution 
and  of  the  precipitated  copper.  The  beaker,  carefully  covered,  sample, 
may  now  be  placed  on  the  top  of  the  air-bath  or  on  a  cool  part 
of  the  sand-bath,  but  the  solution  should  never  be  heated  hotter 
than  60°  or  70°  C,  and  it  should  be  stirred  as  often  as  practicable. 
As  the  most  tedious  part  of  the  determination  of  carbon  in 
steel  is  frequently  that  which  has  to  do  with  the  decomposition 
of  the  steel  and  the  solution  of  the  precipitated  copper,  particularly 
with  low  steels,  the  samples  being  nearly  always  in  lumps,  and  the 
analyst  does  not  wish  to  separate  these  larger  particles  for  fear 
that  the  fine  stuff  alone  may  not  represent  a  true  average,  the 

FIG.  64. 


0      0      ..U 
73 


machine  shown  in  Fig.  64  is  very  useful.  It  consists  of  a  frame- 
work A  of  brass,  cast  in  one  piece  for  the  sake  of  rigidity.  It  is 
fastened  to  the  table  by  lugs  and  screws  not  shown  in  the  cut. 


*  See  page  54. 


f  See  page  37,  "  Factor  Weights." 


150 


ANAL  YSIS   OF  IRON  AND   STEEL. 


Description 
of  stirring- 
machine. 


The  shelf,  on  which  the  beakers  stand,  has  on  it  a  piece  of  asbestos 
board  with  holes  to  fit  exactly  the  bottoms  of  the  beakers  to  pre- 
vent them  from  moving.  To  further  increase  the  stability  of  the 
beakers  (which  should  be  of  very  heavy  glass)  their  bottoms  are 
ground  on  a  glass  plate  with  fine  emery  until  they  have  a  good 
bearing  surface  all  around. 

The  tops,  which  are  covered  when  on  the  machine  with  a 
plate  of  glass,  F,  ground  on  one  side  and  perforated  to  allow  the 
passage  of  the  stirring-rods  E,  are  likewise  ground,  so  that  when 
slightly  moistened  the  ground  glass  prevents  almost  entirely  all 
movement  of  the  covers  on  the  beakers  when  the  machine  is  in 
motion. 

The  small  wooden  pulleys  C  are  fitted  with  brass  spindles, 
which  run  through  the  upper  cross-piece  and  have  on  their  lower 
ends  pieces  of  rubber  tubing,  which  serve  to  hold  the  stirring-rods. 
The  stirring-rods  are  bent  as  shown  in  the  cut,  to  give  the  proper 
motion  to  the  liquid.  A  small  motor,  B,  adapted  to  the  strength 
of  the  current,  furnishes  the  requisite  power.  The  motor,  if 
properly  wound,  may  be  attached  to  an  ordinary  incandescent 
lighting  current,  but  a  sewing-machine  motor  run  by  a  dipping 
battery  of  three  bichromate  cells  is  sufficient  to  give  the  necessary 
number  of  revolutions. 

Necessity  The  fact  that  it  is  not  only  unnecessary  to  use  a  neutral  so- 

latingthe  lution,  but  that  the  use  of  a  neutral  solution  gives  inaccurate 
solutlon-  results,  seems  now  to  be  thoroughly  established  by  the  experi- 
ments of  the  American  members  of  the  International  Steel 
Standard  Committee.  The  best  practice  is  to  add  about  10  per 
cent  of  HC1  to  the  solution  of  double  chloride.  The  reactions 
occurring  may  be  considered  as  Fe  -f  CuCl2—  FeCl2  -f-  Cu  and 
Cu  +  CuCl2  =  2CuCl.  The  part  taken  by  the  chloride  of  am- 
monium does  not  seem  very  clear,  but  the  fact  remains  that 
the  precipitated  copper  is  much  more  soluble  in  the  double 
chloride  of  copper  and  ammonium  than  in  any  other  menstruum. 
When  the  precipitated  copper  is  all,  or  very  nearly  all,  dis- 


DETERMINATION  OF   TOTAL    CARBON. 


FIG.  65. 


solved,  which  is  usually  the  case  in  half  an  hour  after  the  so- 
lution of  double  chloride  of  copper  and  ammonium  is  added  to 
the  drillings,  run  a  little 
of  the  acidulated  double 
chloride  by  means  of  the 
rod  around  the  sides  of 
the  beaker,  wash  off  the 
rod  into  the  beaker  with 
a  jet  of  water,  and  let 
the  beaker  stand  for  a 
few  minutes  to  allow  the 
carbonaceous  matter  to 
settle.*  The  best  form 
of  filtering-apparatus  is 
shown  in  the  annexed 
sketches.  It  consists  of 
the  perforated  platinum 
boat  (Fig.  65),  which  fits  in  the  platinum  holder.  To  prepare 
the  boat  for  use,  place  it  in  the  holder,  as  shown  in  Fig.  66, 
attach  the  pump,  but  do  not  start  it.  Fill  the  boat  with  pre- 
pared asbestosf- suspended  in  water,  pour  enough  around  the 
outside  of  the  boat  to  fill  the  space  a,  Fig.  66,  and  start  the 
filter-pump.  Continue  pouring  the  suspended  asbestos  into  the 
space  a,  Fig.  66,  until  enough  is  drawn  into  the  joint  to  make 
a  good  packing.  By  pressing  it  in  all  round  with  a  spatula 
the  joint  may  be  made  very  tight.  Pour  enough  of  the  sus- 
pended asbestos  into  the  boat  to  make  a  good,  thick  felt,  and 
.press  it  down  firmly  all  over  the  bottom  of  the  boat  with 
something  like  the  square  end  of  a  lead-pencil,  to  make  it 
compact.  Detach  the  pump,  remove  the  boat  from  the  holder 
carefully  so  as  to  leave  the  packing  on  the  sides  of  the  holder, 

*  Barba  suggests  adding  to  the  solution  ignited  asbestos  in  water  to  make  the 
carbonaceous  matter  settle  and  to  prevent  its  clogging  the  filter.  This  is  a  most 
admirable  suggestion  and  should  be  generally  adopted.  f  See  page  26. 


Filtering  on 
perforated 
platinum 
boat. 


Method  of 
preparing 
the  boat. 


152 


ANAL  YSIS   OF  IRON  AND   STEEL. 


and  move  it  up  with  the  end  of  a  spatula,  so  that  it  will  re- 
main as  shown  in  Fig.  65.  Place  another  boat  in  the  holder, 
press  the  packing  into  the  joint  a,  Fig.  66,  with  the  end  of  a 
spatula,  fill  the  boat  with  suspended  asbestos,  and  start  the 


FIG.  66. 


pump.  If  necessary,  pour  a  little  of  the  finer  suspended  as- 
bestos fibre  into  the  joint  to  make  it  perfectly  tight,  and  pre- 
pare the  felt  in  the  boat  as  before.  Dry  the  boats,  and  ignite 
them  in  the  combustion-tube,  two  at  a  time,  in  a  current  of 
oxygen.  Fit  one  of  these  prepared  boats  in  the  holder,  press 
the  packing  into  the  joint  as  before,  first  moistening  it  slightly 
if  it  has  become  dry,  start  the  pump,  and  pour  into  the  boat 
enough  suspended  asbestos,  which  has  been  ignited  in  oxygen, 


DETERMINATION  OF   TOTAL    CARBON. 

to  form  a  thin  film  on  the  top  of  the  felt.  This  film  will  hold 
the  silica,  phosphate  of  iron,  etc.,  from  the  carbonaceous  resi- 
due, and,  after  the  combustion,  will  usually  turn  up  at  the  edges, 
so  that  it  can  be  readily  detached  from  the  main  felt,  leaving 
the  boat  ready  for  another  filtration. 

The  boat  being  thus  prepared,  pour  into  it  the  solution  of  the 
iron  or  steel,  guiding  the  stream  by  a  small  glass  rod  held  against  pared 
the  tip  of  the  beaker.  The  solution,  if  the  joint  a,  Fig.  66,  is 
tight,  and  the  pump  works  well,  will  usually  run  through  the  felt 
as  rapidly  as  it  can  be  poured  into  the  boat.  When  the  super- 
natant fluid  has  all  run  through,  transfer  the  carbonaceous  matter 
to  the  boat  by  a  fine  stream  of  cold  water  from  a  washing-flask. 
Pour  into  the  beaker  about  10  c.c.  of  dilute  hydrochloric  acid,  run 
it  all  around  the  inside  of  the  beaker  by  means  of  the  rod  to  dis- 
solve any  adhering  salt,  wash  off  the  glass  rod  and  wash  down 
the  sides  of  the  beaker  with  a  jet  of  water,  and  decant  the  acid  into 
the  boat,  filling  the  boat  almost  up  to  the  edge.  Wash  the  car- 
bonaceous matter  in  the  boat  thoroughly  with  hot  water  by  filling 
the  boat  from  the  beaker  and  allowing  it  to  suck  through  dry, 
but  do  not  attempt  to  throw  a  jet  of  water  into  the  boat  from  the 
washing-flask,  as.it  will  be  almost  certain  to  throw  some  of  the 
carbonaceous  matter  from  the  boat  or  cause  it  to  crawl  over  the 
side.  In  decanting  the  water  from  the  beaker,  the  lip  must  not 
be  allowed  to  touch  the  surface  of  the  liquid  in  the  boat,  as  a 
film  of  carbonaceous  matter  will  run  up  the  inside  of  the  beaker. 
Pour  a  little  dilute  acid  into  the  joint  between  the  boat  and  holder, 
allow  it  to  suck  through  the  packing,  and  wash  it  several  times 
with  hot  water.  The  carbonaceous  matter  from  pig-iron,  pud-  Differences 
died  iron,  spiegel,  ferro-manganese,  and  ingot  steel  usually  washes  filtration 
like  sand,  but  that  from  steel  which  has  been  hardened,  tempered, 
hammered,  or  rolled  is  apt  to  be  more  or  less  gummy,  stopping 
the  filter  and  rendering  the  filtration  and  washing  prolonged  and 
tedious.  It  is  also  apt  to  adhere  more  or  less  to  the  sides  of  the 
beaker,  and  must  be  wiped  off  by  a  little  wad  of  ignited  fibrous 


154 


ANAL  YSIS   OF  IRON  AND   STEEL. 


FlG 


FIG.  68. 


asbestos,  held  in  a  pair  of  platinum-pointed  forceps  like  those 
shown  in  Fig.  67.     This  wad  is  then  placed  in  the  boat.     When 

the  carbonaceous  matter  is 
thoroughly  washed  and 
sucked  dry,  detach  the  pump, 
remove  the  boat  from  the  holder,  wipe  it  off  carefully  with  a  piece 
of  silk,  place  it  in  a  dish  covered  with  a  watch-glass,  and  dry  it 
in  a  water-bath  or  in  an  air-bath  at  100°  C.  When  dry,  insert 
the  boat  in  the  tube  (Fig.  61),  and  burn  off  the  carbon  as  directed 
Platinum  on  page  146.  Instead  of  the  porcelain  tube,  a  platinum  tube  of 

combus-  IT  •  i  •       -.—.        /- 

tion-tube.    the  dimensions  shown  in  Fig.  69  may  be  used  to  very  great  advan- 
tage.    The  rear  end  has  a  ground  joint  (Fig.  68),  which  may  be 

made  perfectly  air-tight.  The  tube  has 
a  strengthening  band  of  German  silver  at 
B,  Fig.  69,  and  the  part  P,  which  is  of 
phosphor-bronze,  is  ground  in.  To  pre- 
vent the  tube  from  sagging  when  it  is 

hot,  the  rear  end  is  supported  at  P,  Fig.  69,  by  a  wire  from  the 
top  of  the  hood.  A  piece  of  platinum  gauze  ^  inch  long  (12 
mm.),  rolled  up  rather  loosely,  fills  the  forward  end  of  the  tube, 
then  the  tube  is  filled  for  a  distance  of  about  6  inches  (150  mm.) 
with  granular  oxide  of  copper,  followed  by  another  piece  of  plat- 
inum gauze  of  the  same  size  as  the  first,  and  a  similar  roll  2  inches 
long,  with  a  loop,  is  pushed  in  after  the  boat,  the  rear  end  coming 
just  forward  of  the  screen  L.  The  limb  of  the  U-tube  G  nearest 
the  platinum  tube  contains  anhydrous  cupric  sulphate*  and  the 
forward  limb  anhydrous  cuprous  chloride.f  H  contains  dried,  not 
fused,  chloride  of  calcium,  and  in  the  bulb  next  to  G  is  a  small 
wad  of  cotton-wool,  which  should  be  moistened  with  a  single  drop 
of  water  before  each  set  of  combustions.  G  and  H  are  called  the 
purifying  train,  and  when  the  apparatus  is  not  in  use  they  should 
be  detached  from  the  tube  and  the  ends  closed  with  pieces  of 


The  purify- 
ing train. 


*  See  page  53. 


f  See  page  53. 


DETERMINATION  OF   TOTAL    CARBON. 


155 


ANALYSIS   OF  IRON  AND   Sl^EEL. 

glass  rod.  The  object  of  the  cuprous  chloride  is  to  absorb  any 
chlorine  that  may  come  over  during  the  combustion.  If  any 
should  come  over  it  would  be  mixed  with  hydrochloric  acid  and 
moisture,  and  all  then  would  be  absorbed  by  the  salts  in  the  tube 
G.  If  the  carbonaceous  residue  is  properly  washed  it  will  be 
found  necessary  to  renew  the  salts  in  G  only  after  it  has  been 
used  for  25  or  30  combustions.* 
Necessity  for  Before  making  a  combustion,  or  series  of  combustions,  the 

burning 

out  the  tube  should  be  well  burned  out  by  heating  it  to  redness  and  pass- 
fo^mak.  ing  a  current  of  oxygen  through  the  apparatus,  heating  the  small 
bMdon°m"  tuke  S  reci-hot  at  the  same  time  by  means  of  a  small  blast-lamp 
or  Bunsen  burner.  During  this  operation  fumes  of  sulphuric  acid 
issue  from  the  end  of  S,  and  usually,  when  the  flame  of  the  lamp 
is  carried  out  to  this  point,  it  is  colored  green,  showing  that  a 
small  amount  of  copper  salt  is  also  volatilized.  In  making  a 
combustion  the  platinum  should  not  be  heated  above  a  low  red, 
as  at  a  high  temperature  platinum  becomes  permeable  by  CO2. 
The  burners  in  the  furnace  should  be  lighted  in  the  order  directed 
on  page  137,  and,  after  they  are  all  lighted,  ten  minutes  are  ample 
to  burn  off  the  carbonaceous  matter  in  the  boat.  From  the  time 
of  putting  in  the  boat,  fifty  minutes  are  ample  for  finishing  the 
combustion,  including  the  displacement  of  the  oxygen  by  air. 

Instead    of  the   arrangement   of  bottles    F,  F  for  forcing  air 
Cylinder        through   the  apparatus  shown  in  Fig.  61,  a  second  cylinder  con- 

of  com- 
pressed taining  air  under  pressure,  as  shown  in  Fig.  69,  is  much  more  sat- 
isfactory, as  the  current  can  be  controlled  with  perfect  accuracy, 
the  trouble  of  siphoning  the  water  from  the  lower  bottle  is 
avoided,  and  there  is  no  danger  of  passing  gases  or  fumes  from 
the  laboratory  into  the  apparatus. 

The  time  required  when  using  a  porcelain  tube  is  somewhat 
longer,  owing  to  the  danger  incurred  of  cracking  the  tube  if  the 

*  For  a  detailed  account  of  the  experiments  on  determination  of  carbon  in  steel 
see  Prof.  Langley's  paper,  Transactions  of  the  Inst.  of  Mining  Eng.,  Pittsburg  Inter- 
national Meeting,  October,  1890,  and  Jour,  of  Anal,  and  App.  Chem.,  1891,  page  121. 


air. 


DETERMINATION  OF   TOTAL    CARBON.  157 

heat  is  increased  or  diminished  too  rapidly.  A  platinum  tube 
shorter  than  the  one  here  figured  is  not  to  be  recommended,  as 
it  cannot  contain  enough  oxygen  to  burn  the  carbon  to  CO2,  and 
a  consequent  loss  is  often  unavoidable.  Duplicate  results  by  this 
method  should  rarely  vary  more  than  .005  of  a  per  cent,  carbon. 
When  using  3  grammes  of  the  sample,  the  percentage  of  carbon 
is  obtained  by  dividing  the  weight  of  CO2  by  1 1  and  multiplying 
by  100. 

Instead   of  the  perforated   boat   and   holder   described   above,   Filtering  in 

.  a  platinum 

the  carbonaceous  residue  may  be  filtered  in  a  small  platinum  filtering- 
tube  fitting  inside  the  combustion-tube.  It  is  made  as  represented 
in  Fig.  70.  The  small  perforated  disk  of  platinum  rests  on  a  seat 
in  the  tube  as  shown  in  the  sketch.  The  felt  in  the  disk  p1G>  7a 
is  prepared  in  the  same  way  as  directed  for  the  boat, 
and,  after  drying  the  carbonaceous  residue,  the  disk  is 
moved  upward  in  the  filtering-tube  before  inserting  the 
latter  in  the  combustion-tube,  to  allow  the  gas  to  pass 
through  the  filtering-tube  during  the  combustion.  The 
boat  has  several  advantages  over  the  filtering-tube,  the 
principal  one  being  that  the  boat  has  a  much  larger  filtering-sur- 
face, and,  besidesr  there  is  no  danger  of  the  felt  being  disturbed 
during  the  filtering,  while  the  disk  in  the  tube  may  be  loosened 
in  its  seat  and  allow  some  of  the  carbonaceous  matter  to  pass 
around  it.  If  the  boats  when  not  in  use  are  kept  carefully 
covered,  the  same  felts  may  be  used  for  a  large  number  of 
filtrations;  but  occasionally  they  become  clogged,  and  then  it  is 
better  to  renew  them. 

Instead  of  either  of  these  forms  of  filtering-apparatus,  a  sim-  Glass  filter- 
pie  glass  tube,  as  represented  in  Fig.  71,  may  be  used.  The 
closely-coiled  spiral  of  platinum  wire  fits  in  the  tube  as  shown 
in  the  sketch.  On  this  is  placed  a  rather  thick  layer  of  ignited 
long-fibre  asbestos,  and  ignited  asbestos  suspended  in  water  is 
poured  over  it  to  make  a  solid  felt.  The  tube  may  be  used  in 
a  stand,  as  represented  in  Fig.  72,  or  it  may  be  used  with  the 


158 


ANALYSIS   OF  IRON  AND   STEEL. 


filter-pump    under   very   gentle   pressure.      Filter    and    wash    the 
carbonaceous   matter,  and  while  still  moist  transfer  it  to  the  boat 


FIG.  71. 


C 


FIG.  72. 


(Fig.  73)  by  opening  out  the  sides  of  the  boat,  inverting  the  tube 
over  it,  and  allowing  the  felt  and  spiral  to  slide  out  of  the  tube. 
Wipe  off  any  carbonaceous  matter  that  may  remain  on  the  sides 

FIG.  73- 


Boats  of 
platinum- 
foil. 


of  the  tube,  or  that  may  have  adhered  to  the  spiral  in  removing 
it,  with  little  wads  of  fibrous  asbestos  held  in  the  forceps  (Fig.  67). 
Place  these  wads  in  the  boat,  bend  the  sides  of  the  latter  into 


DETERMINATION  OF   TOTAL    CARBON. 


159 


their  proper  shape,  dry  the  boat  and  contents  at  100°  C,  insert 
the  boat  in  the  porcelain  or  platinum  tube,  and  burn  off  the 
carbonaceous  matter  as  before  directed.  This  boat  is  made  by 
cutting  a  piece  of  platinum-foil  in  the  shape  shown  in  Fig.  74, 
and  bending  it  up  over  a  brass  former  into  the  shape  shown 

in  Fig.  73. 

FIG.  74- 


Instead  of  burning  the  carbonaceous  matter  in  a  current  of   combustion 


oxygen,  it  may  be  burned  by  H2SO4  and  CrO3  in  the  arrange- 
ment shown  in  Fig.  75.  P'  is  an  empty  U-tube,  O  is  a  tube 
containing  sulphate  of  silver  dissolved  in  strong  H2SO4,  P  con- 
tains anhydrous  sulphate  of  copper,  Q  granular  dried  chloride 
of  calcium,*  the  Liebig  bulb  and  drying-tube  R  constitute  the 
absorption  apparatus,  S  is  the  safety-guard  tube,  and  L,  L  con- 
stitute the  arrangement  for  passing  air  through  the  apparatus. 
The  air  is  freed  from  CO2  in  passing  through  the  U-tube  M 
filled  with  lumps  of  fused  caustic  potassa.  Transfer  the  carbo- 
naceous matter  and  asbestos  to  the  flask  A,  insert  the  stopper 
carrying  the  bulb-tube  B,  close  the  stopcock  C,  and  connect 
the  apparatus  as  shown  in  Fig.  75,  including  the  weighed  ab- 
sorption apparatus.  See  that  the  joints  are  all  tight,  and  then 
pour  into  B  10  c.c.  of  a  saturated  solution  of  chromic  acid,  ad- 
mit it  to  the  flask  A  by  opening  the  stopcock  C,  and  then  pour 


of  the 

residue 

inCrO8 

and 

H2S04. 


*  The  bulb  of  Q  contains  a  wad  of  slightly  moistened  cotton-wool,  as  described 
on  page  137. 


i6o 


ANALYSIS   OF  IRON  AND  STEEL. 


DETERMINATION  OF   TOTAL    CARBON.  l^l 

into  B  100  c.c.  strong  H2SO4  which  has  been  heated  almost  to 
boiling  with  a  little  CrO3.  Let  this  run  into  A  slowly,  connect 
the  air-apparatus  by  the  tube  N,  and  start  a  slow  current  of  air 
through.  Light  a  very  low  light  under  A,  and  increase  it  grad- 
ually until  the  liquid  is  heated  to  the  boiling-point.  Gradually 
lower  the  light  while  the  current  of  air  continues  to  pass,  and 
when  about  I  litre  of  air  has  passed  through  the  apparatus  after 
the  light  is  extinguished,  detach  and  weigh  the  absorption  ap- 
paratus, with  the  precautions  mentioned  on  page  146. 

The   carbonaceous  residue   may  also  be  weighed  directly  in-  weighing 
stead    of  being  burned   off.     In  this    method,  filter   on  a  Gooch     residue* 
crucible  or  on  counterpoised  filters,*  dry  at   IOO°  C,  and  weigh. 
Burn    off  the  carbonaceous    matter   and  weigh   the    residue :  the 
difference  between  the  two  weights  is  carbonaceous  matter,  which 
contains  about  70  per  cent,  of  carbon  f  in  steel  or  iron  free  from 
graphite.     Of  course  this  method  of  direct  weighing  is  applicable 
only  to  samples  when  all  the  carbon  is  in  the  so-called  combined 
condition. 

2.  Solution  in  Chloride  of  Copper  and  Chloride  of  Potassium, 
Filtration,  and  Combustion  of  the  Residue  in  Oxygen. 

As  a  solvent  this  salt  has  no  advantage  over  the  ammonium 
salt,  but  the  presence  of  carbonaceous  matter  in  the  latter,  which 
can  only  be  removed  by  repeated  crystallizations,  has  brought  the 
potassium  salt  into  use.  Solution  is  almost,  if  not  quite,  as  rapid  Advantages 

.  of  the  po- 

with  the  potassium  salt  as  with  the  ammonium  salt,  and  the  price 
is  decidedly  in  favor  of  the  former.  The  absence  of  volatile  con- 
stituents is  another  advantage,  for  it  is  quite  possible  that  chlo- 
ride of  ammonium  if  left  in  the  carbonaceous  residue  may  be 
decomposed  in  the  red-hot  oxide  of  copper  and  form  some  com- 
pound capable  of  being  absorbed  by  the  caustic  potassa  in  the 
Liebig  bulb  of  the  absorption  apparatus.  The  only  satisfactory 

*  See  page  27.  f  Amer.  Chem.  Jour.,  iii.  245. 

II 


:62  ANALYSIS   OF  IRON  AND   STEEL. 

way  to  test  a  solution  of  double  chloride  is  to  make  several  deter- 
minations on  a  standard  steel  with  each  fresh  lot  of  the  solvent. 

3.  Solution   in  Chloride  of  Copper,  and  Combustion   of  the 

Residue. 

The  only  disadvantage  in  the  use  of  this  reagent  is  the 
length  of  time  required  to  dissolve  a  sample  of  steel  in  it.  Even 
with  a  strongly  acid  solution  and  constant  stirring,  unless  the 
sample  is  very  finely  divided,  it  may  require  several  days  for  its 
complete  solution. 

4.  Solution    in    Iodine    or    Bromine,    and    Combustion    with 

Chromate  of  Lead,  or  "Weighing,  of  the  Residue. 

The  determination  by  this  method,  when  iodine  is  used,  is 
carried  out  exactly  as  directed  for  the  estimation  of  "  Slag  and 
Oxides,"  page  79,  the  residue  being  filtered  on  asbestos,  dried, 
and  burned  with  chromate  of  lead  or  oxide  of  copper,  as  directed 
Weighing  in  A.  2,  page  132  et  seq.  The  residue  may  also  be  filtered  on 
dueeresi  a  counterpoised  filter*  or  Gooch  crucible,  washed,  dried  at  100° 
C,  weighed,  the  carbonaceous  matter  burned  off,  and  the  resi- 
due weighed.  The  difference  between  the  weights  is  the  amount 
of  carbonaceous  matter,  which  contains,  according  to  Eggertz,f 
59  per  cent,  of  carbon.  It  also  contains  about  16  per  cent,  of 
iodine,  so  that  the  residue  cannot  be  burned  in  a  current  of 
oxygen,  nor  with  CrO3  and  H2SO4.  If  bromine  is  used  instead 
of  iodine,  great  care  must  be  taken  in  adding  the  bromine,  10 
c.c.  bromine  for  5  grammes  of  iron  or  steel,  as  the  action  is 
very  violent,  and  unless  the  bromine  is  added  very  slowly  and 
the  solution  kept  as  near  o°  C.  as  possible,  there  will  be  oxida- 
tion, and,  consequently,  loss  of  carbon.  The  details  of  the 
method  when  bromine  is  used  are  otherwise  the  same  as  when 
iodine  is  the  solvent. 

*  See  page  27. 

f  Percy,  Iron  and  Steel,  page  891. 


DETERMINATION  OF  TOTAL    CARBON. 

5.  Solution  by  Fused  Chloride  of  Silver,  and  Combustion  of 

the  Residue. 

Fuse  in  a  porcelain  crucible  20  grammes  of  chloride  of  silver,  Details 
and  see  that  the  button  when  cold  has  a  smooth,  flat  surface  on  method, 
top.  Place  the  button  in  a  porcelain  dish  about  6  inches  ( 1 5  cm.) 
in  diameter,  and  pour  on  the  button  3  grammes  of  drillings.  Add 
300  c.c.  cold  distilled  water  containing  2  drops  of  HC1,  place  the 
dish  on  a  ground-glass  plate,  and  cover  it  with  a  bell-glass  to 
exclude  the  air  during  the  time  occupied  in  dissolving  the  sample. 
It  is  not  necessary  that  the  sample  should  be  in  drillings,  as  a 
single  piece  will  be  dissolved  in  this  way.  The  chloride  of  silver 
should  weigh  at  least  6  times  as  much  as  the  sample  of  iron  or 
steel.  The  reaction  is  a  simple  substitution,  Fe+ 2AgCl  — FeQ2 
-f-  2Ag,  by  galvanic  action,  but  secondary  reactions  occur,  including 
the  decomposition  of  water,  both  hydrogen  and  oxygen  being 
taken  up  by  the  carbon  at  the  moment  of  its  liberation.  A  slight 
excess  of  oxygen  over  the  amount  necessary  to  form  water  with 
the  hydrogen  is  taken  up  and  a  little  hydrogen  is  liberated. 
There  is  a  tendency,  of  course,  for  the  ferrous  chloride  when 
formed  to  oxidize,  consequently  the  air  must  be  excluded.  The 
decomposition  requires  several  days,  as  many  as  ten  if  the  sample 
of  steel  or  iron  is  in  a  single  piece  and  not  very  thin.  The 
metallic  silver  is  quite  cohesive,  and  is  readily  separated  from  the 
carbonaceous  residue.  When  the  action  is  finished,  remove  the 
mass  of  silver,  washing  off  any  of  the  carbonaceous  matter  ad- 
hering to  it,  add  a  little  HC1  to  dissolve  any  ferric  oxide  which 
may  have  formed,  filter  off,  and  burn  the  carbonaceous  matter  by 
one  of  the  methods  previously  described. 

6.  Solution  of  the   Iron   in    Sulphate  of  Copper,    Filtration, 

and  Combustion  of  the  Residue  in  a  Boat  in  a  Current 
of  Oxygen. 

Weigh  3  grammes  of  steel  into  a  No.  3  beaker,  and  add  150 
c.c.  of  solution  of  sulphate  of  copper,  made  by  dissolving   200 


164 


ANALYSIS   OF  IRON  AND   STEEL. 


Prepara- 
tion of 
sulphate 
of  copper 
solution. 


grammes  of  the  copper  salt  in  water,  adding  a  dilute  solution  of 
caustic  soda  until  a  slight  permanent  precipitate  appears,  allowing 
it  to  settle,  filtering  through  asbestos,  and  diluting  to  I  litre.  For 
pig-iron,  spiegel,  and  ferro-manganese,  use  I  gramme,  and  50  c.c. 
of  sulphate  of  copper  solution.  Heat  the  solution  gently,  and  stir 
well  until  decomposition  is  complete.  Filter  in  a  glass  filtering- 
tube  on  asbestos,  as  described  on  page  157.  Wash  well  with 
water,  transfer  to  a  boat,  as  directed  on  page  158,  dry,  and  burn 
in  a  porcelain  tube,  as  directed  for  A.  I,  page  131.  The  results 
are  apt  to  be  a'  little  low,  owing  to  the  difficulty  of  thoroughly 
oxidizing  the  mass  of  copper  mixed  with  the  carbonaceous 
matter.* 

Instead  of  filtering  off  the  mass  of  copper,  carbonaceous  matter, 
etc.,  decant  the  clear  supernatant  fluid  through  the  filtering-tube, 
wash  several  times  by  decantation,  and  then  dissolve  the  copper 
in  double  chloride  of  copper  and  ammonium,  chloride  of  copper, 
or  ferric  chloride.  Filter,  wash  the  residue  with  a  little  dilute 
HC1,  and  then  with  cold  water,  transfer  to  a  boat,  and  burn  as 
directed  on  page  142  et  seq. 

7.    Solution  of  the   Iron  in   Sulphate  of  Copper,  and   Oxida- 
tion of  the   Residue  by  CrO3  +  H2SO4, 

Treat  the  sample  with  solution  of  sulphate  of  copper,  as  in 
the  method  just  described.  Allow  the  precipitated  copper  and 
carbonaceous  matter  to  settle,  pour  off  the  clear  supernatant 
liquid,  and  transfer  the  residue  to  the  flask  A  (Fig.  75,  page  160) 
by  means  of  a  platinum  spatula  and  a  fine  jet  of  water.  The 
water  used  should  not  exceed  20  or  25  c.c.f  The  apparatus  is 
that  sketched  in  Fig.  75,  the  only  difference  being  that  the  tube 

*  See  report  of  the  U.  S.  Board  appointed  to  test  iron,  steel,  and  other  metals, 
vol.  i.  p.  284. 

f  The  borings  may  be  treated  with  the  sulphate  of  copper  solution  in  the  flask 
A,  and  the  clear  liquid  drawn  off  with  a  pipette.  This  will  avoid  the  necessity  for 
transferring  the  residue. 


DETERMINATION  OF   TOTAL    CARBON. 


i65 


O  contains  merely  a  little  strong  H2SO4. 
exactly  as  described  on  page  159. 


Effect  the  combustion 


FIG.  76. 


Description 
of  the  ap- 
paratus. 


8.  Solution  in  Dilute  HC1  by  the  Aid  of  an  Electric  Current, 
and  Combustion  of  the  Residue. 

The  arrangement  shown  in   Fig.  76  may  be  used  in  carry- 
ing  out  the   details  of  this   method.      It   consists  of  a   Nc.  3 
Griffin's  beaker,  in  which   is  a  piece   of  platinum-foil,  the  wire 
from  which  connects  with   the  negative  pole  of  the  battery;    a 
small  basket  of  very  fine  platinum    gauze  is  supported  from  a 
platinum   wire,  on    one   end    of 
which    is    a    clamp    connecting 
with    the   positive   pole   of    the 
battery.     The  battery  is  usually 
a  single   Bunsen  or  Grove   ele- 
ment, and  the  intensity  of  the 
current  should  be  regulated  by 
varying    the    distance    between 
the  foil  and  the  basket,  or   by 
introducing     resistance-coils     in 
the  connections,  so  that  no  gas 
is  given  off  from  the  iron.     Hy- 
drogen, of  course,  is  given  off 
abundantly  from  the  surface  of 

the  foil,  and  the  iron  dissolves  in  the  acid  as  ferrous  chloride. 
Weigh  into  the  basket  from  i  to  5  grammes  of  the  sample, 
which  should  be  in  pieces  and  not  in  powder.  Suspend  the 
basket  from  the  wire,  having  previously  connected  the  rest  of  Details 
the  apparatus  and  poured  into  the  beaker  a  mixture  of  200  c.c. 
water  and  50  c.c.  HC1,  and  regulate  the  intensity  of  the  cur- 
rent as  directed  above.  When  solution  is  complete,  remove  the 
foil  from  the  liquid,  wash  the  carbonaceous  matter  from  the 
basket  with  a  jet  of  cold  water,  and  determine  the  amount  of 
carbon  by  one  of  the  methods  previously  given. 


of  the 
method. 


1 66  ANALYSIS   OF  IRON  AND   STEEL. 

DETERMINATION   OP    GRAPHITIC    CARBON. 

Karsten  gave  the  first  information  in  regard  to  the  existence 
of  graphite  in  pig-iron,  and  he  suggested  dissolving  the  sample 
in  HNO3  with  the  addition  of  a  few  drops  of  HC1,  in  HC1  alone, 
or  in  dilute  H2SO4,  boiling  the  residue  with  caustic  potassa,  filter- 
ing, washing  again  with  HC1,  and  finally  with  water,  and  weighing 
the  residue  as  graphite.  A  very  interesting  comparison  of  the 
results  obtained  by  the  use  of  different  solvents  is  given  by 
Drown,*  and  many  experiments  seem  to  show  that  the  amount  of 
graphite  found  varies  with  the  different  acids  used  to  dissolve  the 
sample,  and  also  with  the  variations  of  treatment  when  the  same 
Solution  acid  is  used.  The  usual  method  is  as  follows :  Treat  I  gramme 
of  pig-iron  or  10  grammes  of  steel  with  an  excess  of  HC1,  i.i 
sp.  gr.  When  all  the  iron  is  dissolved,  boil  for  a  few  minutes, 
allow  the  graphite  to  settle,  and  decant  the  supernatant  fluid  on 
an  asbestos  filter,  using  either  the  perforated  boat,  Fig.  66,  or 
the  filtering-tube,  Figs.  70  and  71.  Wash  several  times  with  hot 
water  by  decantation,  then  pour  on  the  residue  in  the  beaker  30 
c.c.  of  a  solution  of  caustic  potassa,  sp.  gr.  i.i,  and,  when  the  effer- 
vescence ceases,  heat  the  solution  to  boiling.  Filter  on  the  same 
filter,  transfer  the  graphite,  etc.,  to  the  filter,  wash  with  hot  water 
again,  and  finally  with  alcohol  and  ether.  Burn  the  graphite  by 
one  of  the  methods  given  under  "  Determination  of  Total  Carbon," 
and  from  the  weight  of  CO2  obtained  calculate  the  percentage 
Comparison  of  carbon  existing  as  graphite.  It  frequently  happens,  when  the 
obtaTntd5  sample  is  a  high  steel,  that  the  residue  which  remains  after  treat- 
by  dis-  jng  jt  as  above  js  black,  and  contains  carbon,  but  it  is  not  crystal- 
solving 

in  HCI       line  in  appearance,  and  bears  no  resemblance  to  graphite.     The 

and 

HN03.  same  steel  will  dissolve  completely  in  HNO3,  and  when  filtered 
will  not  leave  a  trace  of  carbon  on  the  felt.  Steels  containing 
graphite  give  appreciably  less  carbon  when  dissolved  in  HNO3 
than  when  dissolved  in  HCI.  The  method  giving  probably  the 

*  Trans.  Inst.  Min.  Engineers,  vol.  iii.  p.  42. 


DETERMINATION  OF  COMBINED    CARBON. 


167 


most  accurate  and  certainly  the  most  uniform  results  is  as  fol- 
lows:  Dissolve  the  weighed  sample  in  HNO3,  sp.  gr.  1.2,  using  solution  in 
15  c.c.  of  acid  to  each  gramme  taken  for  analysis.  Filter  on  the 
perforated  boat  or  on  an  ignited  asbestos  filter,  in  a  glass  tube, 
transfer  the  residue  to  the  filter,  and  wash  thoroughly  with  hot 
water.  Treat  the  residue  on  the  filter  with  hot  caustic  potassa 
solution,  i.i  sp.  gr.  (as  the  Si  is  all  oxidized  to  SiO2  there  will  be 
no  effervescence),  wash  thoroughly  with  hot  water,  then  with  a 
little  dilute  HC1,  and  finally  with  hot  water.  Burn  the  carbon  by 
one  of  the  methods  previously  mentioned  and  calculate  the  CO2 
obtained  to  carbon,  and  call  the  result  graphite* 

DETERMINATION    OP    COMBINED    CARBON. 

Indirect  Method- 
Having  determined   the   total   carbon    and  the   graphite,  by 
subtracting  the  latter  from  the  former  we  obtain  the  amount  of 
carbon  existing  in  the  combined  condition. 

Direct  Method. 

This  method  was  first  introduced  by  Eggertz,f  in  1862.  It 
is  based  on  the  fact  that  when  steel  containing  carbon  is  dis- 
solved in  HNO3,  1.2  sp.  gr.,  the  carbon,  which  sometimes  at  first 
separates  out  in  flocks  of  a  brownish  color,  is  eventually  dis- 
solved, giving  to  the  solution  a  depth  of  color  directly  propor- 
tionate to  the  amount  of  combined  carbon  in  the  steel.  To  use 
this  in  practice  it  is  only  necessary  to  determine  accurately  the 
amount  of  combined  carbon  contained  in  a  steel,  by  a  combustion 
method,  and  to  compare  the  depth  of  color  in  a  solution  of  this 
standard  with  that  of  any  unknown  steel,  in  order  to  ascertain  the  Limitatioll 
amount  of  carbon  in  the  latter.  There  is,  however,  a  limitatation  « the  use 

of  this 

in  the  application  of  this  method.     Reference  was  made  on  page     method. 

*  Shimer  (Jour.  Amer.  Chem.  Soc.,  vol.  xvii.  p.  873,  has  shown  that  carbide  of 
titanium  is  insoluble  in  dilute  hydrochloric  acid  and  that  the  nitric  acid  method  is  the 
only  accurate  one  for  the  determination  of  graphite. 

f  Jern-Kontorets  Annaler,  1862,  p.  54;  1874,  p.  176;  1881,  301;  Chem.  News, 
vii.  p.  254;  xliv.  p.  173. 


ANALYSIS   OF  IRON  AND  STEEL. 

129  to  the  fact  that  combined  carbon  is  now  believed  to  exist  in 
two  conditions  in  steel,  or  rather  that  under  circumstances  a  por- 
tion of  the  combined  carbon  changes  its  condition,  and,  from  a 
chemical  point  of  view,  while  it  is  still  combined  carbon,  in  that  it 
is  soluble  in  HNO3,  it  fails  to  impart  so  dark  a  color  to  its  nitric 
acid  solution  as  it  did  in  its  original  state.  The  circumstances 
under  which  a  change  of  this  kind  occurs  are  quite  well  known, 
and  are  merely  those  occasioned  by  the  mechanical  treatment  to 
which  steel  is  submitted,  such  as  hammering,  rolling,  hardening, 
tempering,  etc.*  It  may  be  stated,  then,  as  a  general  proposition, 
that  the  standard  steel  for  the  color-test  should  be  of  the  same  kind 
and  in  the  same  physical  condition  as  the  samples  to  be  tested. 

To  obtain  the  best  results  samples  should  be  taken  from  the 
original  ingots  that  have  not  been  reheated,  rolled,  or  hammered  ; 
Bessemer  steel  should  be  compared  with  Bessemer,  crucible  with 
crucible,  open  hearth  with  open  hearth ;  the  standard  should  con- 
tain approximately  the  same  amount  of  carbon  as  the  samples  to 
be  tested,  and  should  have  as  nearly  as  possible  the  same  chem- 
ical composition.  The  only  elements  that  seem  to  have  any  de- 
cided effect  on  the  color  of  the  nitric  acid  solution  are  copper, 
cobalt,  and  chromium. 

Details  Weigh  out  carefully  .2  gramme  of  each  sample,  including  the 

method  standard,  into  test-tubes  6  inches  (150  mm.)  long  and  ^  inch  (16 
mm.)  in  diameter.  The  test-tubes  should  be  perfectly  clean  and 
dry,  and  each  one  marked  with  the  number  of  the  sample  on  a 
small  gummed  label  near  the  top.  A  little  wooden  rack  (Fig.  77) 
is  convenient  for  holding  the  test-tubes  in  the  weighing-room,  and 
to  avoid  all  chance  of  error  the  tube  is  not  placed  in  the  rack 
until  the  sample  has  been  weighed  and  is  ready  to  be  transferred. 


*  Two  very  interesting  papers  on  this  subject  will  be  found  in  the  Chem.  News, 
J.  S.  Parker,  "On  the  Varying  Condition  of  Carbon  in  Steel,"  xlii.  p.  88;  T.  W. 
Hogg,  "On  the  Condition  of  Carbon  in  Steel,"  xlii.  p.  130.  In  my  own  practice  I 
have  seen  one-third  of  the  total  carbon  changed  from  the  combined  form  to  the 
graphitic  in  a  high  carbon  steel  by  heating  and  hammering  the  ingot. 


DETERMINATION  OF  COMBINED   CARBON.  jfo 

A  little  platinum  or  aluminium  dish  about   \y2  inches  (40  mm.) 
in    diameter,  with  a   spout,  and   furnished  with   a   counterpoise 
(Fig.  44,  page  36),  is  very  convenient  for  holding  the  drillings, 
which    are   brushed    from 
it  into  the  test-tube  with 
a    camel's-hair  brush.     A 
very    excellent    form    of 
water-bath    is    shown    in 
Fig.  78.      It  may  be  pro- 
vided with  a  constant  level 
arrangement,  consisting  of 
a  tubulated  bottle,  the  height  of  the  end  b  of  the  vertical  tube  a  Description 
fixing  the  level   of  the  water  in  the  bath.     A  is  the  bath,  and     bath!*6 
B  the  rack.     The  top  of  the  rack  is  of  sheet-copper,  perforated  to 
receive  the  test-tubes,  the  bottoms  of  which  rest  on  the  coarse 


Q 

C 
7 

r  ^ 

V 

r 

^ 

V 

TJ 

V 

£ 

V 

r 

H 

^ 

i 

V 
i 

I 

(T\ 

Jj 

t 

j 

j> 

i 

^ 

& 

FIG    78. 


copper  gauze,  which  is  joined  to  the  top  by  the  uprights  C.     The 
top  of  the  rack  rests  on  a  flange  around  the  top  of  the  bath. 

Place  the  test-tubes  in  the  rack  B,  and  stand  the  rack  in  the 
bath  which  contains  cold  water.     Drop  into  each  test-tube,  from 


ANALYSIS   OF  IRON  AND   STEEL. 


Amount  of 
HNO8  to 
be  used. 


Apparatus 
for  de- 
livering 
different 
volumes 
of  HNO8. 


FIG.  79. 


a  pipette,  the  proper  amount  of  HNO3,  sp.  gr.  1.2.  For  steels 
containing  less  than  .3  per  cent,  carbon  use  3  c.c.  HNO3;  from 
•3  to  .5  per  cent,  carbon,  4  c.c. ;  from  .5  to  .8  per  cent.,  5  c.c. ; 
from  .8  to  I  per  cent.,  6  c.c. ;  and  over  I  per  cent,  7  c.c.  An 
insufficient  amount  of  acid  gives  the  solution  a  slightly  darker 
tint  than  it  should  properly  have. 

The  apparatus  shown  in  Fig.  79  *  is  useful  for  the  rapid  addi- 
tion of  different  measured  quantities  of  nitric 
acid  to  the  samples. 

It  consists  of  a  glass  reservoir  holding 
750  c.c.,  communicating  below  with  four  bu- 
rettes graduated  to  deliver  various  quantities 
of  acid  up  to  10  c.c.  Each  burette  is  fur- 
nished with  a  loose-fitting  glass  cap.  The 
burettes  are  fitted  with  three-way  glass  stop- 
cocks, so  that  a  quarter  of  a  revolution  con- 
nects them  with  the  reservoir,  and  when  the 
proper  amount  of  acid  has  run  in,  the  stop- 
cock is  turned  another  quarter,  which  shuts 
off  the  reservoir  and  completely  empties  the 
burette,  thus  delivering  the  exact  amount 
of  acid  measured,  into  the  test-tube  contain- 
ing the  weighed  sample  of  steel  in  which 
carbon  is  to  be  determined. 
As  shown  in  the  cut,  each  test-tube  stands  in  a  bottle  of  cold 
water  to  prevent  too  violent  action  of  the  acid  during  solution. 
The  whole  apparatus  is  mounted  on  a  rotary  stand,  and,  as  used 
at  the  laboratory  of  the  Bethlehem  Iron  Company,  is  contained 
in  a  small  hood  near  the  drill  and  balance  described  on  page  16, 
so  that  the  operator,  seated  on  a  revolving  stool,  can  add  acid 
to  one  sample  of  steel  while  the  drillings  of  the  next  sample 
are  falling  into  the  balance-pan. 


*  Communicated  to  the  author. 


DETERMINATION  OF  COMBINED    CARBON.  j^j 

The  apparatus,  as  here  shown,  is  a  modification  by  Mr.  Albert 
L.  Colby,  chemist  of  the  Bethlehem  Iron  Company,  of  an  appa- 
ratus first  designed  by  Mr.  E.  A.  Uehling  in  1884. 

The  HNO3  is  made  by  adding  its  own  volume  of  water  to  Proper 
acid  of  the  usual  strength,  1.4  sp.gr.  It  should  be  absolutely  Of  HNOS. 
free  from  chlorine  or  hydrochloric  acid,  as,  according  to  Eggertz, 
.0001  gramme  Cl  in  a  nitric  acid  solution  of  .1  gramme  iron  in 
2.5  c.c.  HNO3  gives  a  decided  yellow  color.  The  HNO3  should 
be  added  slowly,  to  prevent  violent  action,  and  the  drillings 
should  not  be  too  fine,  for  the  same  reason.  Place  in  the  top 
of  each  test-tube  a  small  glass  bulb  *  or  a  very  small  funnel,  and 
heat  the  water  in  the  bath  to  boiling,  and  boil  until  all  the 
carbonaceous  matter  is  dissolved,  shaking  the  tubes  from  time 
to  time  to  prevent  the  formation  of  any  little  film  of  oxide.  The 
time  required  for  solution  is  for  low  steels  about  twenty  minutes, 
and  for  high  steels  (over  I  per  cent,  carbon)  forty-five  minutes, 
After  entire  solution  of  the  carbonaceous  matter,  prolonged  heat- 
ing tends  to  make  the  color  lighter ;  therefore,  as  soon  as  the 
absence  of  small  bubbles  and  the  disappearance  of  any  brownish 
flocculent  matter  show  complete  solution,  remove  the  rack  from 
the  bath  and  stand  it  in  a  dish  of  cold  water.  The  dish  should 
be  about  the  same  size  as  the  bath,  so  that  the  top  will  be 
covered  by  the  top  of  the  rack,  thus  excluding  the  light  from 
the  solutions,  in  which  case  the  color  will  not  fade  for  a  long 
time.  Under  all  circumstances  the  solutions  should  be  kept  out 
of  the  light,  and  especially  out  of  direct  sunlight,  as  much  as 
possible.  If  there  should  be  necessarily,  in  the  steels  operated 
on  at  one  time,  a  wide  range  in  carbon,  the  test-tubes  should 
be  removed  from  the  bath  as  fast  as  their  respective  contents 
are  dissolved  and  placed  in  cold  water  in  a  dark  place.  The 
appearance  of  the  drillings  will  often  give  an  idea  of  the  approxi- 

*  These  bulbs  are  easily  made  by  sealing  one  end  of  a  glass  tube  in  the  blow- 
pipe flame,  heating  it,  blowing  a  bulb  of  the  proper  size,  allowing  it  to  cool,  heating 
it  above  the  neck,  and  drawing  it  out  as  shown  in  Fig.  77. 


1/2 


ANAL  YSIS   OF  IRON  AND   STEEL. 


Comparing 
the 
colors. 


Compari- 
son-tubes. 


wood's 

modifica- 

tions  for 


mate  carbon  contents  of  a  sample,  but  when  there  is  no  clue 
whatever,  it  is  best  to  begin  by  adding  3  c.c.  HNO3  to  the 
weighed  portion  in  the  test-tube,  and  increase  the  amount 
I  c.c.  at  a  time  as  the  depth  of  color  of  the  solution  or 
the  amount  of  flocculent  carbonaceous  matter  indicates 
a  higher  carbon  percentage.  To  compare  the  colors  of 
the  solutions,  pour  the  standard  into  one  of  the  carbon 
tubes  (Fig.  80),  wash  out  the  test-tube  with  a  little  cold 
water,  add  it  to  the  solution  in  the  carbon  tube,  and 
dilute  to  a  convenient  amount. 

This  dilution  should  be  sufficient  to  make  the  volume 
of  the  diluted  standard  at  least  twice  as  great  as  the 
volume  of  acid  originally  used  to  dissolve  the  sample,  as 
this  amount  of  water  is  necessary  to  destroy  the  color 
due  to  the  nitrate  of  iron.  It  should  not,  however,  greatly 
exceed  this  amount,  and  should  be  in  some  convenient 
multiple  of  the  carbon  contents  of  the  standard  in  tenths 
of  a  per  cent.  Thus,  if  a  standard  contains  .45  per  cent. 
carbon,  dilute  the  solution  in  the  carbon  tube  to  9  c.c.. 
then  each  c.c.  will  equal  .05  per  cent.  The  carbon  tubes 
should  be  about  ]/2  inch  (12  mm.)  in  diameter,  holding  at 
least  30  c.c.,  and  graduated  to  ^  c.c.  The  tubes  should 
have  exactly  the  same  diameter,  and  the  glass  should  be 
perfectly  colorless  and  have  walls  of  the  same  thickness.  They 
should,  of  course,  be  most  accurately  graduated. 

Mr.   E.   F.  Wood,*    of  the    Homestead    Works,    leaves    the 

... 

lower  ends  of  the  tubes  free  from  graduations  to  give  a  clear 
space  for  comparing  the  colors.  He  considers  this  especially 
necessary  in  low  steels,  for  which  he  uses  I  gramme  of  the 
sample,  dissolves  in  25  c.c.  of  nitric  acid,  boils  for  five  to  seven 
minutes  in  a  glycerine  bath  at  140°  C,  and  compares  in  tubes 
Y±  inch  (18  mm.)  in  diameter. 


FIG.  80. 


121 


Communicated  to  the  author. 


DETERMINATION  OF  COMBINED   CARBON. 


173 


The  standard  having  been  prepared,  pour  the  solution  of  the 
sample  to  be  tested  into  another  carbon  tube,  rinse  the  test- 
tube  into  it  with  a  little  cold  water,  and  compare  the  colors. 
If  the  solution  of  the  sample  is  darker  than  that  of  the  stand- 
ard, add  water  little  by  little,  shaking  the  tube  well  to  mix  the 
solution  until  the  shades  are  exactly  the  same.  Allow  a  minute 
or  two  for  the  solution  to  run  down  the  walls  of  the  tube,  and 
read  the  volume.  If  the  standard  was  diluted  as  above,  then, 
of  course,  each  c.c.  will  equal  .05  per  cent,  carbon,  and  if  the 
volume  of  the  sample  is  10.5  c.c.  it  will  contain  .525  per  cent, 
carbon.  If  the  solution  of  the  sample  when  first  transferred  to 
the  tube  should  be  lighter  in  color  than  the  standard,  a  lower 
standard  must  be  used,  or  this  one  may  be  diluted  to,  say,  13.5 
c.c.,  in  which  case  the  number  of  c.c.  divided  by  3  will  give 
the  percentage  of  carbon  in  tenths.  The  color  may  be  com- 
pared by  holding  the  two  tubes  in  front  of  a  piece  of  white 
paper  held  towards  the  light,  but  a  camera  made  of  light  wood 
and  blackened  inside  is  most  convenient,  and  at  night  is  quite 
invaluable.  It  is  shown  in  Fig. 
8 1,  and  consists  of  a  box  3^ 
inches  (90  mm.)  high  inside,  i^ 
inches  (38  mm.)  wide  at  one  end, 
and  5  inches  (127  mm.)  at  the 
other.  It  is  24  inches  (610  mm.) 
long,  and  is  supported  on  a  rod, 
which  can  be  raised  and  lowered 
to  suit  the  convenience  of  the  ob- 
server. The  small  end  is  closed 
by  a  piece  of  ground-glass,  which 
slides  in  through  a  slot  on  top 
I  inch  (25  mm.)  from  the  end. 
Immediately  beyond  this  is  an- 
other slot  to  receive  a  thin  piece  of  faintly  blue  glass,  which  is 
inserted  when  the  tests  are  made  at  night,  using  an  oil-lamp 


FIG.  81. 


Description 
of  camera. 


1y ^  ANALYSIS   OF  IRON  AND   STEEL. 

placed  on  a  stand  just  beyond  the  camera.  In  fact,  in  many 
steel-works,  to  avoid  the  differences  between  the  colors  as  seen 
by  daylight  and  lamplight,  all  comparisons  are  made  in  a  dark 
room,  using  a  box  or  camera  and  an  oil-lamp.  Two  holes  in 
the  top  of  the  camera  just  inside  the  ground-glass  screen  receive 
the  carbon  tubes,  the  ends  of  which  rest  on  a  piece  of  black 
cloth  on  the  bottom  of  the  camera  inside.  Another  piece  of 
black  cloth  fastened  across  the  top  of  the  camera,  covering 
the  top  of  the  ground-glass  slide,  and  having  holes  just  large 
enough  to  admit  the  tubes,  excludes  all  light  except  that  at  the 
back  of  the  tubes.  A  north  light  is  much  the  best  for  com- 
paring the  colors,  and,  as  to  most  observers  the  left-hand  tube 
appears  a  little  the  darker,  the  color  will  be  exactly  matched 
when,  the  tubes  being  reversed,  the  left-hand  tube  still  appears  a 
little  the  darker  of  the  two. 

Use  of  per-  Instead  of  diluting  the  solutions  to  agree  with  a  standard,  as 

^ndards.  above  described,  some  chemists  use  a  rack  of  permanent  stand- 
ards, as  suggested  by  Britton.*  The  principal  difficulty  hereto- 
fore attending  the  use  of  permanent  standards  has  been  the  im- 
possibility of  preventing  their  fading ;  but,  according  to  Eggertz,f 
this  is  now  entirely  overcome  by  the  method  of  preparing  them 
suggested  by  Prof.  F.  L.  Ekman.  The  details  are  as  follows  :  Dis- 
solve 3  grammes  of  neutral  ferric  chloride  in  100  c.c.  water  con- 
taining 1.5  c.c.  HC1;  dissolve  2.1  grammes  cupric  chloride  in  100 
c.c.  water  containing  .5  c.c.  HC1 ;  dissolve  2.1  grammes  cobaltic 
chloride  in  100  c.c.  water  containing  5  c.c.  HC1,  using  the  neutral 

Preparation  salts  in  all  cases.  These  solutions  will  contain  about  .01  gramme 
solution,  of  the  metal  to  the  c.c.,  and  by  adding  to  8  c.c.  of  the  iron  solu- 
tion 6  c.c.  of  the  cobalt  solution,  3  c.c.  of  the  copper  solution, 
and  5  c.c.  water  containing  .5  per  cent  HC1,  a  liquid  is  obtained 
which  has  a  color  approximating  to  that  obtained  by  dissolving 
.2  gramme  of  steel,  containing  I  per  cent,  of  carbon,  in  HNO3,  and 

*  Chem.  News,  xxii.  101.  f  Chem.  News,  xliv.  173. 


DETERMINATION  OF  COMBINED   CARBON.  ij$ 

diluting  to   10  c.c.,  or  .1  per  cent,  carbon  to  the  c.c.     Prepare  a 

number  of  test-tubes  of  the  size  described  on  page   168,  but  in 

this  case  it  is  essential  that  they  should  be  of  exactly  the  same 

diameter,  and  that  the  glass  should  be  as  nearly  colorless  as  pos- 

sible.    By  successive  dilutions  with  water  containing  .5  per  cent.  Preparation 

HC1,  of  the  normal  solution  prepared  as  above,  make  solutions  of      standards. 

about  the  proper  strength  for  the  series  required. 

The  variations  should  be  about  .02  per  cent,  between  the  differ- 
ent tubes  of  the  series,  corresponding  to,  say,  the  even  hundredths. 
There  should  be  about  10  c.c.  of  solution  in  each  tube,  and  then 
the  color  of  each  should  be  compared  with  a  standard  steel, 
diluted  to  the  exact  strength  required  in  the  permanent  standard. 
For  example,  if  the  standard  steel  contains  .4  per  cent,  carbon,  and 
you  wish  to  get  the  exact  color  for  the  .32  per  cent,  carbon  tube 
in  the  permanent  series,  then  dissolve  .2  gramme  of  the  standard 
exactly  as  directed  on  page  170,  pour  the  solution  into  a  carbon 
tube,  and  dilute  it  in  accordance  with  the  formula,  carbon  required 
:  carbon  of  standard  :  :  10  c.c.  :  the  number  of  c.c.  required,  or,  in 
this  case,  32  :  40  :  :  10  c.c.  :  12.5  c.c.  Therefore  dilute  the  solu- 
tion in  the  carbon  tube  to  12.5  c.c.,  pour  10  c.c.  into  a  test-tube 
exactly  like  those  used  for  the  permanent  standards,  and  compare 
it  with  the  .32  per  cent,  carbon  tube.  If  the  color  of  the  perma- 
nent solution  is  not  exactly  the  same,  correct  it  by  adding  por- 
tions of  the  solutions  of  the  iron,  cobalt,  or  copper  salts,  or  water 
containing  .5  per  cent.  HC1.  The  iron  salt  or  HC1  alone  gives  a 
yellowish,  the  cobalt  salt  a  brownish,  and  the  copper  salt  a  green- 

FIG.  82. 


ish,  tone  to  the  solution.  The  standards  may  now  be  arranged  in 
a  rack,  as  shown  in  Fig.  82.  The  colors  of  the  permanent  stand- 
ards once  fixed,  the  samples  to  be  analyzed  are  treated  exactly 


ANALYSIS    OF  IRON  AND   STEEL. 


Details  of 
method 
when 
using  per- 
manent 
standards. 


White  cast 
iron. 


Filtering 
from 
graphite, 
etc. 


Stead's 
method. 


as  described  on  page  170,  the  test-tubes  used  being  precisely  like 
those  containing  the  permanent  standards,  and  each  one  carefully 
graduated  to  contain  10  c.c.  When  the  samples  (.2  gramme  each) 
are  dissolved  and  cooled,  dilute  each  solution  in  turn  with  cold 
water  to  10  c.c.,  mix  thoroughly,  and  compare  it  with  the  stand- 
ards in  the  rack,  by  which  means  the  carbon  may  be  estimated  to 
the  nearest  hundredth  of  a  per  cent. 

In  testing  white  cast  iron,  use  only  .05  gramme,  dissolve  in  7 
c.c.  HNO3,  dilute  the  standard  to  some  convenient  amount  approxi- 
mating 20  c.c.,  and  compare  as  quickly  as  possible  to  avoid  the 
precipitation  of  carbonaceous  matter,  which  is  apt  to  occur  under 
these  circumstances.  The  graphite  in  ordinary  gray  pig-iron,  and 
sometimes  even  in  steels,  renders  filtration  necessary.  In  this  case 
add  to  the  cold  acid  solution  one-half  of  its  volume  of  water,  filter 
through  a  small,  dry,  ashless  filter  into  the  carbon  tube,  wash  with 
as  little  water  as  possible,  and  compare  as  usual. 

For  steels  very  low  in  carbon,  the  color  test,  as  above  described, 
becomes  uncertain,  but  Stead*  has  suggested  and  elaborated  a 
method  which  gives  excellent  results.  It  is  based  on  the  fact  that 
the  carbonaceous  matter  liberated  from  iron  and  steel  is  soluble  in 
the  caustic  alkalies  as  well  as  in  HNO3,  while  the  color  which  it 
imparts  to  the  alkaline  solution  is  about  2^  times  as  great  as  that 
which  it  gives  to  the  acid  solution.  For  this  method  is  required, 
besides  the  HNO3,  1.2  sp.  gr.,  a  solution  of  caustic  soda  1.27  sp.  gr. 
Weigh  I  gramme  of  each  sample,  including  the  standard,  into  a 
No.  I  beaker,  add  12  c.c.  HNOS,  and  heat  on  the  bath  until  solution 
is  complete,  which,  in  the  case  of  puddled  iron  or  low  steel,  is  in 
about  five  or  ten  minutes.  Add  to  each  30  c.c.  of  boiling  water 
and  13  c.c.  of  the  soda  solution,  stirring  well.  Pour  each  solution 
in  turn  into  a  glass  measuring-jar,  dilute  to  60  c.c.,  mix  thor- 
oughly, allow  the  solution  to  settle,  filter  through  a  dry  filter,  and 
receive  15  c.c.  of  each  sample  in  a  carbon  tube.  Those  samples 


*  Jour.  Iron  and  Steel  Institute,  1883,  No.  I,  p.  213. 


DETERMINATION  OF  COMBINED    CARBON. 


177 


whose  solutions  are  darker  than  that  of  the  standard  contain,  of 
course,  more  carbon  than  the  standard.  Dilute  the  solutions  in 
turn  until  the  colors  agree  with  that  of  the  standard.  The  per- 
centage of  carbon  is  deduced  from  the  equation  — x^=^,  in 

which  a  is  the  percentage  of  carbon  in  the  standard,  15,  of  course, 
the  number  of  c.c.  taken  of  each  solution,  b  is  the  number  of  c.c. 
in  the  diluted  sample,  and  x  is  the  percentage  of  carbon  in  the 
sample.  Take  those  samples  whose  solutions  are  lighter  than 
that  of  the  standard,  and  dilute  the  standard  until  its  color  is  the 
same  as  that  of  the  darkest  of 
the  samples,  read  the  volume, 
and  dilute  it  for  the  next  darkest, 
and  so  on  through  the  series. 
The  percentage  of  carbon  in 
each  sample  is  then  deduced 


FIG.  83. 


a 
from  the   equation  -,  X  1  5  = 


13 


ITs 


the  letters  having  the  meaning 

given  above.      They   may   also 

be   compared   by  pouring   into 

measuring-tubes  until  the  colors 

appear   equal   when    looked    at 

from    above.      The    carbon    in 

this    case    is    inversely   as    the 

length  of  the  column.     To  facili- 

tate the  comparison,  Stead  (loc. 

cit.)  has    devised  a  very  simple 

instrument   based   on    this    last 

principle.     It  consists  (Fig.  83) 

of  two  parallel  tubes  of  any  con- 

venient diameter   fastened  to  a 

frame.      The  tube  b  is  open  at  both  ends,  but  is  contracted  at 

the  point  c.     The  contracted  end  passes  through  the  stopper  of 

12 


=L19 

i.18 
1L17 
I.16 

Tl5 


ANALYSIS   OF  IRON  AND   STEEL. 

the  bottle  d,  and  reaches  almost  to  the  bottom  of  the  bottle.  A 
small  tube,  et  which  ends  just  below  the  stopper,  is  connected 
with  a  bulb  syringe,  f.  The  tube  a  is  closed  at  the  lower  end, 
and  contains  a  small,  solid,  glazed  china  cylinder,  which  rests 
on  the  bottom.  A  similar  cylinder  rests  just  above  the  con- 
traction in  the  tube  b,  and  the  tubes  are  so  arranged  that  the 
upper  flat  surfaces  of  the  cylinders  are  on  the  same  level,  and 
exactly  the  same  distance  from  the  open  tops  of  the  tubes.  The 
scale  g  is  graduated  in  .02  up  to  .20  from  the  level  of  the  upper 
surfaces  of  the  cylinders  to  a  point  marked  on  the  tube  a,  10 
inches  (254  mm.)  above.  A  solution  of  a  standard  steel  contain- 
ing .2  per  cent,  carbon,  prepared  as  above,  is  placed  in  the  bottle 
d,  and  a  similar  solution  of  a  sample  to  be  tested  is  poured  into 
the  tube  a  up  to  the  mark.  By  squeezing  the  bulb  f  a  column 
of  the  standard  solution  is  forced  up  the  tube  b,  and  when,  by 
looking  into  the  mirror,  placed  at  an  angle  of  45°,  the  color  in  the 
two  columns  appears  equal  in  intensity,  the  percentage  of  carbon 
is  read  off  on  the  scale  opposite  the  top  of  the  column  in  b.  The 
alkaline  solution  is  said  to  keep  its  color  unaltered  for  a  month 
when  not  exposed  to  direct  sunlight. 


DETERMINATION  OF  TITANIUM. 

By  Precipitation. 

Only  traces  or  very  minute  amounts  of  titanium  are  found 
in  steel,  but  notable  quantities  exist  in  some  kinds  of  pig-iron. 
As  pointed  out  by  Riley,*  when  pig-iron  containing  titanium  is 
dissolved  in  HC1  a  portion  of  the  titanium  goes  into  solution, 
while  the  remainder  is  found  with  the  insoluble  matter.  The 
insoluble  portion,  as  noticed  on  page  86  et  seq.,  contains  P2O5. 
It  is  a  curious  fact  that  while  TiO2  interferes  with  the  deter- 

*  Jour.  Chem.  Soc.,  xvi.  387. 


DETERMINATION  OF   TITANIUM. 

mination  of  P2O5  by  its  tendency  to  form   upon  evaporation   to  insoluble 

phospho- 

dryness    an    insoluble    phospho-titanate,  so    P2O5  interferes   with 


the  determination  of  TiO2  by  partially  preventing  the  precipita- 

tion of  TiO2  from  its  boiling  sulphuric  acid  solution.     The  best  Separation 

method-  therefore,  for  the  determination  of  titanium  is  to  proceed 

exactly  as  for  the   determination   of  phosphorus  when   titanium 

is  present,  as  directed  on  page  86  et  seq.,  until  the  residue  from 

the  aqueous  solution   of  the  carbonate  of  sodium  fusion  is   ob- 

tained.    Dry  this  residue,  transfer  it  to  a  large  platinum  crucible, 

preferably  the  one  in  which  the  carbonate  of  sodium  fusion  was 

made,  burn  the  filter,  add  its   ash  to  the   residue,  and  fuse   the 

whole  with  15  or  20  times  its  weight  of  bisulphate  of  potassium. 

In  fusing  with  bisulphate  of  potassium  it  is  necessary  to   begin  Fusion 

with  a  very  low  heat,  and  to  raise  the  temperature  very  slowly     KHSO* 

and    carefully  to    a  low  red  heat,  as  the    mixture    has    a  strong 

tendency  to  boil  over  the  top  of  the  crucible  whenever  the  tem- 

perature is  increased  too  rapidly.     When  the  lid  of  the  crucible 

is  raised,  fumes  of  SO3  should  come  orT,  and  the  fusion  should 

be  kept  at  this  point  for  several  hours,  or  until  it  is  quite  clear 

and   the  whole   of  the  ferric  oxide   has   been  dissolved.     Incline 

the  crucible  as  far  as  possible  on  one  side  while  the  fused  mass 

is    still  liquid,  and  allow  it   to  cool  in  this  position.     The   mass 

will  harden   in  a   cake  on  the  side  of  the  crucible,  and  can  be 

readily  detached  without  bending  the  sides  of  the  crucible.    Place 

the    crucible   and   lid   in    a  No.    4   beaker,    and   suspend   in   the 

beaker   a  little  platinum  wire-gauze   basket  containing   the  fused 

mass,  as  shown  in  Fig.  76,  page    165.     Pour  into  the  beaker  50 

c.c.  of  strong  sulphurous  acid  water,  and  fill  the  beaker  to   the 

top  of  the  fused  mass    in  the  basket  with  cold  water.     Under  Solution  of 

the  bisul- 

these  circumstances  the  fused  mass  dissolves  quite  rapidly,  as 
the  concentrated  solution  falls  to  the  bottom,  and  the  iron  is  at 
the  same  time  deoxidized.  Without  the  basket,  it  is  necessary 
to  stir  the  liquid  constantly,  and  the  time  occupied  in  dis- 
solving the  fused  mass  is  much  prolonged.  When  solution  is 


ANALYSIS   OF  IRON  AND   STEEL. 

complete,  remove  the  basket,  the  crucible,  and  the  lid  from  the 
beaker,  wash  them  with  a  jet  of  cold  water,  and  filter  the  solu- 
tion into  a  No.  5  beaker.  Add  a  filtered  solution  of  20  grammes 
acetate  of  sodium  and  one-sixth  the  volume  of  the  solution  of 
acetic  acid,  1.04  sp.  gr.,  to  the  filtered  solution,  and  heat  to 
boiling.  The  titanic  acid  is  precipitated  almost  immediately  in  a 
flocculent  condition,  and  quite  free  from  iron.  Boil  for  a  few 
minutes,  allow  the  titanic  acid  to  settle,  filter,  wash  with  hot 
water  containing  a  little  acetic  acid,  dry,  ignite,  and  weigh  as 
TiO2,  which  contains  60.00  per  cent.  Ti.  Instead  of  fusing  the 
residue  from  the  aqueous  solution  of  the  carbonate  of  sodium 
fusion  with  bisulphate  of  potassium,  the  operation  may  be  hast- 
ened as  follows  : 

Treatment  Transfer  the  residue  to  the  large  crucible,  as  before  directed, 

th  and  fuse  with  5  grammes    of  dry  carbonate  of  sodium.     Allow 


H2so4.  tke  crucify  f-0  cool,  ancj  then  pour  into  it  very  gradually  strong 
H2SO4.  When  the  effervescence  slackens,  warm  the  crucible 
slightly,  and  continue  the  addition  of  H2SO4  and  the  careful 
application  of  heat  until  the  fusion  becomes  liquid  and  the  ferric 
oxide  is  all  dissolved.  Heat  carefully  until  copious  fumes  of 
SO3  are  given  off,  allow  the  crucible  to  cool,  and  pour  the  con- 
tents, which  should  be  just  fluid  when  cold,  into  a  beaker  con- 
taining about  250  c.c.  of  cold  water.  Add  to  it  50  c.c.  of  a 
strong  aqueous  solution  of  sulphurous  acid,  or  2  or  3  c.c.  of 
bisulphite  of  ammonium,  filter  if  necessary,  nearly  neutralize  by 
NH4HO,  allow  it  to  stand  until  it  is  entirely  decolorized,  add  20 
grammes  acetate  of  sodium  and  one-sixth  its  volume  of  acetic 
acid,  1.04  sp.  gr.,  and  precipitate  the  TiO2  as  before. 

By  Volatilization. 

Drown*  suggested  the    method    of  determining  titanium  by 
volatilizing    it  in  a  current    of  chlorine    gas.     The    details,  with 

*  Trans.  Inst.  Min.  Engineers,  viii.  508. 


DETERMINATION  OF  COPPER. 

some  modifications,  are  as  follows.  Treat  the  sample  exactly  as 
directed  for  the  determination  of  silicon,  by  volatilization  in  a 
current  of  chlorine  gas,  page  73  et  seq. 

To  the  filtrate  from  the  silica,  page  76,  add  a  slight  excess 
of  NH4HO,  acidulate  with  acetic  acid,  boil,  filter,  wash,  and 
ignite  the  precipitate.  As  this  precipitate  may  contain  a  little 
ferric  oxide  (carried  over  mechanically  as  Fe2Cl6),  phosphoric 
acid,  tungstic  acid,  etc.,  fuse  it  with  a  little  carbonate  of  sodium, 
dissolve  the  fused  mass  in  hot  water,  filter,  wash,  dry,  and  ignite 
the  residue,  which  will  contain  all  the  titanic  acid  as  titanate  of 
sodium,  and  any  iron  that  may  have  been  present  as  Fe2O3. 
The  filtrate  will  contain  the  P2O5,  etc.  Fuse  the  ignited  residue 
with  a  little  carbonate  of  sodium,  treat  it  in  the  crucible  with 
strong  H2SO4,  as  directed  on  page  180,  and  determine  the  TiO2 
in  the  manner  there  described. 


DETERMINATION    OF    COPPER. 

For  the  determination  of  copper  the  precipitate  by  H2S,  ob- 
tained in  the  determination  of  phosphorus,  page  84,  may  be  used, 
but  in  this  case  the  precipitate  must  be  filtered  off  before  getting 
rid  of  the  excess  of  H2S,  after  which,  if  any  additional  precipi- 
tate of  As2S3  is  thrown  down  in  the  filtrate,  it  must  be  filtered  off 
before  proceeding  with  the  determination  of  phosphorus.  Dry 
and  ignite  the  filter  with  the  precipitate  of  CuS,  etc.,  in  a  porce- 
lain crucible,  burn  off  all  the  carbon  from  the  paper,  allow  the 
crucible  to  cool,  and  digest  the  precipitate  at  a  gentle  heat  with 
HNO3  and  a  few  drops  of  H2SO4,  keeping  the  crucible  covered 
with  a  small  watch-glass.  When  the  CuS  is  entirely  dissolved, 
remove  the  watch-glass  and  evaporate  the  solution  until  all  the 
HNO3  is  expelled  and  fumes  of  SO3  are  given  off.  Allow  it  to 
cool,  add  enough  water  to  dissolve  all  the  CuSO4,  heating  gently, 


182 


ANALYSIS   OF  IRON  AND   STEEL. 


if    necessary,  and  wash  the    solution    into    a   platinum    crucible. 
-     Place  the  crucible  in  the  little  brass  holder  (Fig.  84),  and  attach 
eiectroiy-    the   weighed   platinum    cylinder   and    connect  the  battery.     The 
battery  should  consist  of  three  Daniell's  2-quart  cells,  arranged 
as  shown  in  Fig.  85.     The  connectors  a,  b  pass  through  the  sides 
of  the  box  (which  should  be  kept  covered),  and,  the  jars  being 

FIG.  84. 


Zn 


connected  as  shown  in  the  sketch,  by  simply  changing  the  wire 
from  a  to  b,  three  cells  are  brought  into  action  instead  of  two. 
For  depositing  the  small  amount  of  copper  found  in  iron  or  steel, 
two  cells  furnish  a  sufficiently  strong  current.  The  platinum  cyl- 
inder should  weigh  about  3  or  4  grammes;  it  is  lowered  into 
the  liquid  until  it  is  just  clear  of  the  bottom  of  the  crucible,  and 
the  crucible  is  covered  with  two  small  pieces  of  glass  to  prevent 
liquid  being  carried  off  by  the  escaping  gas.  It  is  much  neater 
to  deposit  the  copper  on  the  cylinder  than  in  the  crucible,  as  it 
weighs  less,  is  quite  as  easy  to  wash  and  dry,  and  there  is  no 
danger  of  any  silica  or  dirt  from  the  solution  being  covered  by 
the  deposited  copper.  When  the  copper  is  all  deposited,  usu- 
ally in  two  or  three  hours,  remove  the  cylinder,  wash  it  with 
cold  water,  then  with  alcohol,  dry  at  100°  C,  cool,  and  weigh. 
The  increase  of  weight  is  Cu. 


DETERMINATION  OF  COPPER.  ^ 

In    pig-irons   containing    titanium   it   is   necessary   to    use   a  Using  solu- 
tion from 
separate  portion  for  the  determination  of  copper.     In  steels,  the     s,  deter- 

solution  in  the  flask  from  the  determination  of  sulphur  (page  61)     ™stedsn 
may  be  used  for  the  determination  of  copper.     In  this  case,  wash 
the  contents  of  the  flask  into  a  No.  5  beaker,  nearly  neutralize 
with  NH4HO,  add  5  c.c.  HC1,  heat  the  solution  to  boiling,  and 
pass  H2S  through  the  boiling  solution  for  fifteen  or  twenty  min- 
utes, filter,  wash  with   hot  water,   and   treat   the   precipitate   as 
directed  above.     In  the  case  of  pig-irons,  however,  it  is  best  to  Procedure 
dissolve  in  aqua  regia,  evaporate  to  dryness,  redissolve  in  HC1,     iron. 
filter,  reduce  the  iron  in  the  filtrate  with  NH4HSO3,  boil  off  the 
excess  of  SO2,  and  precipitate  by  H2S.     Instead  of  using  H2S, 
the  copper  may  be  precipitated  in  a  sulphuric  acid  solution  by 
hyposulphite   of  sodium.     Dissolve  5  grammes  of  the  sample  in   Predpita- 

tion  by 

a  mixture  of  150  c.c.   H2O   and    12  c.c.  strong   H2SO4.     Dilute 


to  about  500  c.c.  with  hot  water,  heat  to  boiling,  and  add  3 
grammes  of  hyposulphite  of  sodium  dissolved  in  10  c.c.  hot 
water.  Boil  for  a  few  minutes,  allow  the  precipitate  to  settle, 
and  filter  and  wash  with  hot  water.  Dry  the  precipitate,  which 
besides  the  CuS  will  consist  of  the  graphite,  silica,  etc.  ;  transfer 
it  to  a  small  beaker,  burn  the  filter,  and  add  the  ash  to  the  main 
portion.  Digest  the  whole  with  aqua  regia,  dilute  with  hot 
water,  filter,  wash,  add  a  few  drops  of  H2SO4,  and  evaporate 
until  fumes  of  SO3  are  given  ofT,  cool,  dissolve  in  water,  transfer 
to  the  platinum  crucible,  and  determine  the  copper  by  the  battery 
as  directed  above. 

Instead  of  determining  the  copper  by  electrolysis,  it  may  be 
determined  as  subsulphide,  Cu2S,  or  as  oxide,  CuO.  To  deter-  GUSS. 
mine  it  as  Cu2S,  dilute  the  sulphate  obtained  by  any  of  the 
methods  mentioned  above  with  water  to  about  50  c.c.,  add  an 
excess  of  NH4HO,  filter  from  Fe2O3,  etc.,  wash  with  ammoniacal 
water,  and  pass  H2S  through  the  cold  solution.  Filter,  wash 
with  H2S  water,  dry  the  filter  and  precipitate,  transfer  the  latter 
to  a  small  porcelain  crucible,  burn  the  filter,  and  add  its  ash  to 


tion  as 


1 84 


Determina- 
tion as 
CuO. 


ANALYSIS   OF  IRON  AND   STEEL. 

the  precipitate.  Add  to  the  precipitate  in  the  crucible  about 
twice  its  volume  of  flowers  of  sulphur  and  ignite  it  in  a  current 
of  hydrogen,  as  directed  for  the  determination  of  manganese 
as  MnS,  page  114.  Weigh  as  Cu2S,  which  contains  79.82  per 
cent.  Cu. 

Instead  of  igniting  the  precipitate  obtained  above  as  Cu2S, 
the  copper  may  be  determined  as  CuO,  as  follows :  Dissolve  the 
sulphide  in  aqua  regia  in  a  small  porcelain  dish,  evaporate  nearly 
dry,  dilute  with  hot  water,  heat  to  boiling,  and  add  a  slight 
excess  of  a  dilute  solution  of  caustic  soda  or  potassa.  Filter  on 
a  small  ashless  filter,  wash  with  hot  water,  dry,  transfer  the  pre- 
cipitate to  a  platinum  crucible,  burn  the  filter  and  add  its  ash 
to  the  precipitate,  moisten  the  whole  with  HNO3,  and  heat  very 
gently  at  first,  but  increase  the  heat  slowly  to  redness.  Cool, 
and  weigh  as  CuO,  which  contains  79.85  per  cent.  Cu. 


Separation 
from  Cu. 


DETERMINATION    OF    NICKEL    AND    COBALT. 

Treat  3  grammes  of  the  drillings  exactly  as  directed  for  the 
determination  of  manganese  by  the  acetate  method,  page  103  et 
seq.  The  precipitate  by  H2S,  page  112,  will  contain  all  the  nickel 
and  cobalt  and  a  portion  of  the  copper  contained  in  the  sample. 
Filter  this  precipitate  on  a  small  washed  filter,  wash  with  H2S 
water  containing  a  little  free  acetic  acid,  dry  and  ignite  the  filter 
and  precipitate,  and  transfer  them  to  a  No.  I  beaker.  Dissolve 
in  HC1  with  a  few  drops  of  HNO3,  evaporate  to  dryness,  redis- 
solve  in  10-20  drops  of  HC1,  dilute  with  hot  water  to  about  50 
c.c.,  heat  the  solution  to  boiling,  and  pass  a  stream  of  H2S 
through  the  boiling  solution  to  precipitate  any  copper  that  may 
be  present.  Filter,  wash  with  hot  water,  evaporate  the  filtrate  to 
dryness,  moisten  the  dry  mass  with  4  or  5  drops  of  HC1,  add  20 
or  30  drops  of  cold  water,  and  then  2  or  3  grammes  of  nitrite 


DETERMINATION  OF  NICKEL   AND    COBALT.  185 

of  potassium  (KNO2)  *  dissolved  in  the  least  possible  amount  of 
water,  and  acidulated  with  acetic  acid.     The  presence   of  cobalt  separation 
is  shown  by  the  formation  of  a  bright  yellow  precipitate  of  the     GO. 
double  nitrite  of  cobalt  and  potassium,  (KNO2)6Co2(NO2)6  -f-  Aq. 
Stir  the  solution,  and  allow  it  to  stand  twenty-four  hours,  with 
occasional    stirring.     Filter  on  a   small  ashless  filter,  wash  with 
water    containing   acetate    of  potassium  and  a  little   free   acetic 
acid,  remove  the  filtrate  which  contains  the  nickel,  and  wash  the 
precipitate  and  filter  free  from  acetate  of  potassium  with  alcohol. 
Ignite  the  filter  and  precipitate  carefully  in  a  porcelain  crucible, 

.  r  .  i    •      i  r 

being  careful  not  to  raise  the  temperature  high  enough  to  fuse 

the   precipitate;  transfer   to  a  very   small   beaker,  and  digest   in 

HCl  and   a   little    KClO3.     Evaporate   to    dryness,   redissolve   in 

3-5  drops  of  HCl,  dilute  with  cold  water,  add  about  I  gramme 

of  acetate   of  sodium,  and  boil   for   an   hour   to  precipitate   the 

small  amount  of  Fe2O3  and  Al2O3  that  is  always  present.     Filter, 

to  the  filtrate  add  excess  of  NH4HO  and  NH4HS,  and  heat  to 

boiling.     As    soon  as  the  precipitate   of  CoS  has    settled,  filter, 

wash  with  water  containing  a  little  NH4HS,  dry  and  ignite  the 

precipitate  and  filter,  in  a  platinum  crucible.     When  all  the  car- 

bon is  burned,  allow  the  crucible  to  cool,  pour  in  a  little  HNO3, 

heat   carefully,  and    finally   evaporate   to    dryness.      Add   a   few  AsCoSO4. 

drops  of  H2SO4,  digest  until  the  sulphide  and  oxide  are  changed 

to  sulphate  of  cobalt,  drive  off  the  excess  of  H2SO4,  heat  finally 

to  dull  redness  for  a  few  moments,  cool,  and  weigh  as  CoSO4, 

which  contains  38.05  per  cent,  of  cobalt.     Heat  the  filtrate  from 

the   double    nitrate  of  cobalt   and   potassium   to   boiling,  add   a 

slight   excess    of  caustic   potassa,  boil  for  a  few  minutes,    filter, 

and  wash  the  precipitate  of  oxide  of  nickel  with  hot  water.     Dis- 


solve  the  precipitate  on  the  filter  with  HCl,  allow  the  solution 
to  run  back  into  the  beaker  in  which  the  oxide  of  nickel  was 
precipitated,  and  wash  the  filter  with  hot  water.  Evaporate 


See  page  47. 


1 86 


ANALYSIS   OF  IRON  AND   STEEL. 


As  Ni2S  or 
NiO. 


Determina- 
tion by 
electroly- 
sis as  Ni 
+  Co. 


Determina- 
of  Co. 


Determina- 

of  Ni. 


the  solution  to  dryness,  redissolve  in  3-5  drops  of  HC1,  dilute 
with  cold  water  to  about  50  c.c.,  add  about  I  gramme  of  ace- 
tate of  sodium,  boil  for  about  an  hour,  filter  off  any  Fe2O3  and 
A12O3,  and  wash  with  hot  water.  To  the  filtrate  add  an  excess 
of  NH4HS  (a  brown  color  shows  the  presence  of  nickel),  acid- 
ulate with  acetic  acid,  heat  to  boiling,  and  pass  a  current  of 
H2S  through  the  boiling  solution  until  the  precipitated  sulphur 
and  sulphide  of  nickel  agglomerate.  Filter,  wash  with  H2S  water, 
dry  and  ignite  the  filter,  and  precipitate.  Allow  the  crucible 
to  cool,  add  a  little  carbonate  of  ammonium  to  the  precipitate, 
heat  to  dull  redness,  and  volatilize  any  sulphuric  acid  that  may 
have  been  formed  as  sulphate  of  ammonium,  cool,  and  weigh  as 
Ni2S  or  NiO,  which  contains  78.55  per  cent,  of  nickel.  The 
nickel  and  cobalt  may  also  be  weighed  in  the  metallic  condi- 
tion by  precipitating  them  by  the  battery  from  the  ammoniacal 
solutions  of  the  sulphates.  If  it  is  not  desired  to  separate  them, 
evaporate  the  filtrate  from  the  precipitated  sulphide  of  copper 
with  an  excess  of  H2SO4  until  the  HC1  is  driven  off  and  fumes 
of  SO3  appear,  allow  the  beaker  to  cool,  add  about  5  c.c.  water, 
then  an  excess  of  NH4HO,  filter  if  necessary,  transfer  to  a  plat- 
inum crucible,  and  precipitate  on  the  small  cylinder  (Fig.  84, 
page  176)  in  a  strongly  ammoniacal  solution,  using  three  cells  of 
the  battery.  Wash  the  cylinder  with  water,  then  with  alcohol, 
dry  at  100°  C,  and  weigh  as  Ni -f-  Co.  To  determine  the  nickel 
and  cobalt  separately,  precipitate  the  cobalt  as  double  nitrite  of 
cobalt  and  potassium,  treat  the  ignited  cobalt  precipitate  with 
an  excess  of  H2SO4,  heat  until  fumes  of  SO3  are  given  off,  di- 
lute a  little,  make  the  solution  strongly  ammoniacal,  and  pre- 
cipitate the  cobalt  as  above  directed.  Precipitate  the  NiO,  in 
the  filtrate  from  the  cobalt,  by  KHO  solution,  filter,  wash,  dis- 
solve on  the  filter  in  HC1,  evaporate  the  solution  with  H2SO4, 
add  excess  of  NH4HO,  and  precipitate  the  Ni  by  the  battery 
as  above. 

For  the  analysis  of  nickel  steel,  which  contains  from  2  to  3  per 


DETERMINATION  OF  CHROMIUM  AND  ALUMINIUM.  187 

cent,  of  nickel,  use  I  gramme  of  the  sample,  and,  after  obtaining  Nickel  steel, 
the  precipitate  of  NiS  as  described  above,  burn  it  with  the  filter  in 
a  porcelain  crucible,  allow  it  to  cool,  add  a  little  pure  powdered 
sulphur,  and  ignite  in  a  stream  of  hydrogen  gas  as  described  on 
page  114.     Weigh  as  Ni2S. 


DETERMINATION    OF   CHROMIUM    AND   ALU- 
MINIUM. 

Weigh  5  grammes  of  drillings  into  a  flask  of  about  500  c.c. 
capacity,  and  pour  in  20  c.c.  strong  HC1  diluted  with  3  or  4  times 
its  bulk  of  water.  Close  the  flask  with  a  rubber  stopper  carrying 
a  valve  which  is  made  as  follows.  Bore  a  hole  through  the  centre  Bunsen 
of  a  rubber  stopper,  and  insert  a  piece  of  glass  tubing  long  enough 
to  extend  from  the  small  end  of  the  stopper  to  a  distance  of  I  inch 
(25  mm.)  beyond  the  large  end.  Take  a  piece  of  heavy  soft  rubber 
tubing  2  inches  (50  mm.)  long,  and  cut  a  longitudinal  slit  in  the 
middle  about  ^  inch  (12  mm.)  long.  Close  one  end  of  the  tube 
with  a  piece  of  glass  rod  ^  inch  (12  mm.)  long,  and  fit  the  other 
end  over  the  glass  tube  in  the  stopper  for  a  distance  of  J^  inch 
(12  mm.).  This  valve  allows  the  gas  to  escape  from  the  flask,  but 
prevents  air  from  entering  it,  so  that  the  iron  is  not  oxidized,  but 
remains  dissolved  as  ferrous  chloride.  Heat  the  dilute  acid  in  the 
flask  if  necessary,  and  when  the  iron  or  steel  is  entirely  dissolved 
remove  the  stopper,  drop  a  small  piece  of  Na2CO3  into  the  flask, 
and  close  it  with  a  solid  rubber  stopper.  Cool  the  flask  with  its 
contents  as  quickly  as  possible,  and  dilute  the  solution  with  cold 
water  until  the  flask  is  three-fourths  full.  Add  BaCO3,*  shaking 
constantly  until  the  solution  appears  milky  with  the  excess  of 
BaCO3.  Loosen  the  stopper  to  allow  the  CO2  to  escape,  shake 

*  See  page  50. 


i88 


ANALYSIS   OF  IRON  AND   STEEL. 


Cr  and  Al 
insoluble 
in  HC1. 


Separation 
of  Cr  and 
Al  from 
Feby 
NH4HS. 


Separation 
of  Cr  and 
Alby 
Dexter's 
method. 


the  flask  at  intervals  for  several  hours,  and  allow  it  to  stand  over- 
night, the  stopper  being  pushed  well  into  the  neck.  The  precipi- 
tate will  consist  of  all  the  A12O3,  Cr2O3,  Fe2O3  from  the  solution,  as 
well  as  P2O5,  etc.,  and  the  graphite  and  silica  that  were  insoluble  in 
the  dilute  acid ;  it  should  be  quite  white  from  the  excess  of  BaCO3 
added.  Filter  as  rapidly  as  possible,  wash  with  cold  water,  dis- 
solve on  the  filter  in  dilute  HC1,  allow  the  solution  to  run  into  a 
small  beaker,  clean  out  the  flask  with  the  same  acid,  and  wash  it 
and  the  filter  well  with  hot  water.  The  insoluble  matter  left  on 
the  filter  may  contain  some  chromium  and  aluminium  insoluble  in 
dilute  HC1,  and  usually  in  the  form  of  slag,  or  in  puddled  iron  as 
oxides.  This  may  be  ignited,  treated  with  HF1  and  H2SO4,  evapo- 
rated to  dryness,  fused  with  Na2CO3  and  KNO3,  and  the  Cr2O3  and 
A12O3  determined,  or  the  solution  of  the  fused  mass  in  dilute  HC1 
added  to  the  filtrate  from  the  insoluble  matter.  Boil  this  filtrate, 
add  a  slight  excess  of  H2SO4  to  precipitate  all  the  barium,  allow 
the  precipitate  of  BaSO4  to  settle,  filter,  and  wash  with  hot  water. 
Evaporate  the  filtrate  to  get  rid  of  the  excess  of  acid,  dilute  with 
cold  water,  add  sufficient  tartaric  or  citric  acid  to  hold  the  iron  in 
solution,  add  an  excess  of  NH4HO,  and  to  the  solution,  which 
should  be  perfectly  clear,  an  excess  of  NH4HS.  Allow  the  pre- 
cipitated FeS  to  settle,  filter,  wash  with  water  containing  NH4HS, 
evaporate  the  filtrate  to  dryness  in  a  large  platinum  crucible,  heat 
to  redness  to  volatilize  the  ammonium  salts,  and  burn  the  carbon 
formed  from  the  decomposition  of  the  tartaric  acid.  Fuse  the 
residue  with  6  parts  Na2CO3  and  I  part  KNO3,  dissolve  out  in 
water,*  transfer  to  a  beaker,  add  2  or  3  grammes  KC1O3,  rinse  out 
the  crucible  with  HC1,  add  it  to  the  solution,  and  then  add  a  slight 
excess  of  HC1.  Evaporate  to  syrupy  consistency  on  the  water- 
bath,  adding  a  little  KC1O3  from  time  to  time  to  decompose  the 
excess  of  HCl.f  Redissolve  in  water,  add  an  excess  of  carbonate 

*  If  the  fusion  or  its  concentrated  aqueous  solution  is  not  yellowish  in  color 
there  is  no  chromium  present. 

f  Dexter,  Pogg.  Annal.,  89,  142. 


DETERMINATION  OF  CHROMIUM  AND   ALUMINIUM. 

of  ammonium  to  precipitate  the  A12O3,  and  boil  off  all  smell  of 
ammonia.  The  alumina  will  be  precipitated  as  phosphate,  wholly 
or  in  part,  if  the  sample  contains  phosphorus,  while  the  chromium 
is  in  solution  as  chromate  of  potassium  or  sodium.  Filter,  wash 
with  hot  water,  reserve  the  filtrate  and  washings,  redissolve  the 
precipitate  on  the  filter  in  HC1,  allowing  the  solution  to  run  into 
a  small  beaker,  evaporate  to  dryness  to  render  any  silica  insoluble, 
redissolve  in  HC1,  filter,  to  the  filtrate  add  excess  of  NH4HO  and 
NH4HS,  boil,  filter  on  a  small  ashless  filter,  wash  with  hot  water, 
ignite,  and  weigh  as  A12O3,  which  contains  53.01  per  cent.  Al. 
Acidulate  the  solution  containing  the  chromium  with  HC1,  heat  to 
decompose  the  excess  of  KC1O3,  add  a  little  alcohol,  and  evaporate 
to  dryness  to  render  silica  insoluble.  The  chromium  is  now  in  Determina- 
the  condition  of  Cr2O3;  redissolve  in  HC1,  dilute,  filter  off  any 
silica  that  may  be  present,  to  the  filtrate  add  an  excess  of  NH4HO, 
boil,  filter  on  a  small  ashless  filter,  wash  well  with  hot  water,  ignite, 
and  weigh  as  Cr2O3,  which  contains  68.48  per  cent,  of  chromium. 
As  the  precipitates  of  A12O3  and  Cr2O3  may  both  contain  P2O5,  it  is 
necessary  to  fuse  each  of  them,  after  weighing,  with  a  little  Na2CO3, 
dissolve  in  water,  filter,  acidulate  with  HNO3,  and  determine  the 
P2O5  by  the  molybdate  method,  or  acidulate  with  HC1*  add  a  little  separation 
citric  acid  and  magnesium  mixture,  and  determine  the  P2O5  as 
Mg2P2O7.  Calculate  the  amount  of  P2O5,  subtract  its  weight  from 
that  of  the  A12O3  and  Cr2O3  respectively,  and  calculate  the  re- 
mainder to  Al  and  Cr,  as  directed  above. 

Instead  of  separating  the  aluminium  and  chromium  by  HC1 
and  KC1O3,  as  directed  above,  the  better  method  suggested  by 
Genth  *  may  be  used,  which  is  as  follows :  Dissolve  in  water 
the  fusion  of  the  residue  from  the  volatilization  of  the  ammonium 
salts  and  the  decomposition  of  the  tartaric  acid,  transfer  it  to  a 
platinum  dish,  add  a  few  grammes  of  nitrate  of  ammonium,  and 
evaporate  down  on  a  water-bath  until  the  solution  is  syrupy, 

*  Chem.  News,  vi.  32. 


ANALYSIS   OF  IRON  AND   STEEL. 

adding  NH4NO3  from  time  to  time  until  the  addition  fails  to 
produce  any  further  evolution  of  NH4HO  from  the  solution. 
Add  a  little  carbonate  of  ammonium  towards  the  end  of  the 
operation,  and  when  the  solution  is  syrupy  and  smells  very 
faintly  of  ammonia,  dilute  and  filter  from  the  A12O3,  which  treat 
as  directed  above.  To  the  filtrate  add  a  strong  aqueous  solution 
of  sulphurous  acid,  boil  off  the  excess  of  SO2,  and  add  NH4HO 
to  alkaline  reaction.  Boil,  filter,  wash,  ignite,  and  weigh  the 
Cr2O3,  which  must  be  tested  for  P2O5  as  above  directed.  To 
a-  determine  chromium  alone  in  iron  or  steel,  treat  5  grammes  with 
alone.  HC1,  precipitate  by  BaCO3,  filter,  and  wash  the  insoluble  matter 
and  precipitate,  as  directed  above.  Place  a  clean  beaker  under 
the  funnel,  pierce  the  filter,  and  wash  the  contents  into  the 
beaker.  Clean  the  flask  and  filter  with  hot  dilute  HC1,  and 
wash  them  thoroughly  with  hot  water,  allowing  all  the  acid  and 
washings  to  run  into  the  beaker.  Add  enough  HC1  to  dissolve 
the  soluble  part  of  the  precipitate  (Fe2O3,  Cr2O3,  A12O3,  BaCO3), 
dilute,  boil,  and  precipitate  the  Cr2O3,  etc.,  with  NH4HO.  Boil 
off  all  smell  of  ammonia,  allow  the  precipitate  to  settle,  and  wash 
well  with  hot  water.  Dry,  and  transfer  the  precipitate  to  a  platinum 
crucible,  carefully  separating  it  from  the  filter,  ignite  the  filter,  and 
add  its  ashes  to  the  precipitate  in  the  crucible.  Before  heating 
the  precipitate,  add  to  it  in  the  crucible  3-6  grammes  Na2CO3 
and  y2  gramme  KNO3  (with  pig-irons  it  is  necessary  to  add  2-3 
grammes  KNO3  to  oxidize  the  graphite),  and  mix  thoroughly. 
Heat  gradually  to  fusion,  and  finally  raise  the  heat  until  all  the 
KNO3  is  decomposed.  Cool,  treat  the  fused  mass  with  hot  water, 
filter  from  Fe2O3,  wash  well  with  hot  water,  acidulate  the  filtrate 
with  HC1,  and  evaporate  to  dryness  with  a  little  alcohol.  Redis- 
solve  in  HC1,  dilute,  filter  from  SiO2,  and  in  the  filtrate  precipitate 
the  Cr2O3  by  NH4HO.  Filter,  wash  thoroughly,  dry,  ignite,  and 
weigh  as  Cr2O3.  This  precipitate  may  contain  also  some  A12O3 
and  P2O5,  which  must  be  separated  in  very  accurate  determina- 
tions, and  the  amounts  subtracted  from  the  first  weight  of  Cr2O3. 


DETERMINATION  OF  CHROMIUM  AND  ALUMINIUM.  IQI 

Determination  of  Aluminium,  Stead's  Method.* 
Weigh  off  6-12  or  24  grammes  steel,  place  in  600  c.c.  beaker, 
cover  with  watch-glass,  dissolve  it  in  HC1  (strong),  evaporate  to 
dryness,  redissolve  in  HC1,  filter  into  1000  c.c.  beaker  through 
an  ashless  filter,  wash  filter  containing  silica,  nearly  neutralize 
the  filtrate  with  dilute  ammonia,  and  boil  filtrate,  which  should 
measure  about  500  to  600  c.c.  Add  to  the  solution  I  or  2  c.c. 
of  saturated  solution  of  ammonium  phosphate,  and  then  a  large 
excess  of  sodium  hyposulphite,  boil  till  all  SO2  has  passed  off 
(half  an  hour's  boiling  should  be  sufficient) ;  just  before  filtering 
add  20  c.c.  of  a  saturated  solution  of  ammonium  acetate,  stir  to 
mix,  and  filter  through  an  ashless  filter,  wash  precipitate  and 
filter  5  or  6  times,  add  to  the  beaker  from  which  the  solution 
and  precipitate  had  been  formed  10  c.c.  HC1,  heat  to  boiling,  re- 
move the  vessel  containing  the  filtrate,  and  place  instead  of  it 
under  the  funnel  a  platinum  dish,  and  pour  over  the  filter  the 
boiling  acid.  Rinse  out  the  beaker  and  wash  all  soluble  mat- 
ter on  the  filter  with  a  fine  jet,  evaporate  the  solution  to  dry- 
ness  in  the  platinum  dish,  and  heat,  to  drive  off  excess  of  acid,  on 
the  sand-bath  to  a  temperature  of  300°  or  400°  F. 

Add  from  2  to  5  grammes  pure  sodium  hydrate  made  from 
sodium  free  from  alumina  and  about  2  c.c.  water.  Heat  gently 
over  a  rose-burner  for  ten  minutes,  maintaining  the  mass  in  a 
fluid  state  all  the  time.  Cool  and  add  water,  and  boil  till  solu- 
tion is  complete.  Make  the  bulk  of  the  solution  to  300  c.c.  and 
note  the  temperature  exactly.  Shake  well  and  filter  through  an 
ashless  filter.  Measure  off  250  c.c.  at  the  original  temperature, 
equal  to  5-10  or  20  grammes  steel.  If  any  yellow  tint  is  ob-  indication 
servable  chromium  may  be  present.  In  such  a  case  the  phos-  mium. 
phate  of  alumina  must  be  neutralized  with  HC1  and  precipitated 
by  ammonium  carbonate,  taking  care  to  boil  the  solution  well 
to  free  from  excess  of  ammonia  before  filtering.  Filter  off 

*  Prepared  by  Mr.  J.  E.  Stead,  of  Middlesboro',  England,  for  this  volume. 


ANALYSIS   OF  IRON  AND   STEEL. 

through  an  ashless  filter,  dry,  burn  off,  and  weigh,  dissolve  pre- 
cipitate in  HC1  and  determine  P2O5  in  it,  and  deduct  the  weight 
found  from  the  weight  of  the  original  precipitate.  If  chromium 
is  absent,  neutralize  the  solution  with  HC1  as  before  described, 
boil  and  add  excess  of  sodium  hyposulphite,  and  boil  for  half 
an  hour,  filter  off  precipitate,  burn,  and  weigh  as  pure  aluminium 
phosphate,  which  contains  22.18  per  cent,  of  aluminium. 

Carnot's  Method.* 

M.  Carnot  states  that  the  method  is  very  similar  to  that  pub- 
lished by  Mr.  J.  E.  Stead  in  the  Journal  of  the  Society  of  Chem- 
ical Industry,  1889,  page  965,  but  that  he  has  used  and  taught 
it  at  the  Ecole  des  Mines  for  eight  years.  It  is  founded  on  the 
reaction  that  he  pointed  out  in  1881,  that  aluminium  is  precipi- 
tated as  the  neutral  phosphate  from  a  boiling  solution  faintly 
acid  with  acetic  acid.  The  precipitation  succeeds  equally  well 
when  the  solution  contains  iron,  if  the  ferric  salt  has  been  pre- 
viously reduced  to  ferrous  by  hyposulphite  of  soda. 

Treat  10  grammes  of  the  iron  or  steel  in  a  platinum  dish 
covered  with  a  piece  of  platinum-foil  with  hydrochloric  acid, 
and  when  solution  is  complete,  dilute  and  filter  into  a  flask, 
washing  the  carbon,  silica,  etc.,  on  the  filter  thoroughly  with 
distilled  water.  Neutralize  the  solution  with  ammonia  and  car- 
bonate of  soda,  but  see  that  no  permanent  precipitate  is  formed, 
then  add  a  little  hyposulphite  of  soda,  and,  when  the  liquid  at 
first  violet  becomes  colorless,  2  or  3  c.c.  of  a  saturated  solution 
of  phosphate  of  soda  and  5  or  6  grammes  of  acetate  of  soda  dis- 
solved in  a  little  water.  Boil  the  solution  about  three-quarters  of 
an  hour,  or  until  it  no  longer  smells  of  sulphurous  acid.  Filter, 
and  wash  the  precipitate  of  phosphate  of  alumina,  mixed  with  a 
little  silica  and  ferric  phosphate,  with  boiling  water.  Treat  the 
precipitate  on  the  filter  with  hot  dilute  hydrochloric  acid,  allow 
the  solution  to  run  into  a  platinum  dish,  evaporate  to  dryness, 


*  A.  Carnot,  Moniteur  Scientifique,   1891,  p.  14. 


DETERMINATION  OF  CHROMIUM  AND  ALUMINIUM.  193 

and  heat  at  100°  for  an  hour  to  render  the  silica  insoluble.  Dis- 
solve in  hot  dilute  hydrochloric  acid,  filter  from  the  silica,  dilute 
to  about  IOO  c.c.  with  cold  water,  neutralize  as  before,  add  a 
little  hyposulphite  in  the  cold,  then  a  mixture  of  2  grammes  of 
hyposulphite  and  2  grammes  of  acetate  of  soda,  wash,  and  weigh 
as  A1PO4,  which  contains  22.18  per  cent,  of  aluminium. 

Determination  of  Chromium.     Volumetric  Method  for 
Chromium. 

Galbraith  *  has  suggested  a  rapid  method  for  the  determina- 
tion of  chromium  when  it  is  present  in  appreciable  amounts,  as 
in  chrome  steel  or  chrome  pig-iron.  Dissolve  1-3  grammes  of 
the  sample  in  dilute  H2SO4  (i  part  H2SO4  and  6  parts  water), 
add  permanganate  of  potassium  in  crystals  until  the  iron  is  all 
oxidized  and  the  liquid  is  quite  red  in  color,  then  add  as  much 
more  to  oxidize  the  chromium  to  CrO3.  Heat  the  solution  to 
boiling,  and  boil  until  the  permanganate  is  all  decomposed  and 
there  remains  a  precipitate  of  oxide  of  manganese.  Filter,  wash 
with  hot  water,  to  the  filtrate  add  a  measured  volume  of  stand- 
ardized ferrous  sulphate,  and  determine  the  excess  of  ferrous 
sulphate  by  a  standard  solution  of  permanganate.  From  the 
amount  of  ferrous  sulphate  oxidized  by  the  CrO3  calculate  the 
amount  of  Cr.  The  reaction  is  6FeSO4+  2CrO3  +  6H2SO4  = 
3Fe2(SO4)3  -f  Cr2(SO4)3  +  6H2O,  or  I  equivalent  of  chromic  acid 
will  oxidize  3  equivalents  of  ferrous  sulphate  to  ferric  sulphate. 
Therefore,  if  the  value  of  the  permanganate  is  known  in  metal- 
lic iron,  and  consequently  the  value  of  the  ferrous  sulphate  (it 
being  standardized  by  the  permanganate)  in  metallic  iron,  the 
amount  of  chromium  is  calculated  as  follows:  3  equiv.  Fe= 
1  68  :  I  equiv.  Cr=  52.14  ::  the  value  of  the  ferrous  sulphate 
oxidized  by  the  CrO3  in  Fe  :  its  value  in  Cr;  or  multiply  the 
value  of  the  ferrous  sulphate  oxidized,  in  Fe,  by  6f$1g*  =  .3103. 


*  Chem.  News,  xxxv.  151. 
13 


ANALYSIS   OF  IRON  AND  STEEL. 

The  titration  is  effected  in  the  manner  directed  for  the  deter- 
mination of  iron  in  iron  ores. 

Barba  *  has  suggested  several  modifications  which  decidedly 

modifica- 
tion,         improve  the  method.    To  avoid  the  large  precipitate  of  manganese 

dioxide,  he  uses  nitric  acid  to  oxidize  the  iron,  having  found  that 
even  a  considerable  excess  of  this  reagent  does  not  effect  the 
subsequent  reactions.  He  uses,  most  successfully,  ammonia  to 
destroy  the  excess  of  potassium  permanganate.  The  method  is 
as  follows : 

Dissolve  1.25  grammes  steel  in  20  c.c.  sulphuric  acid  1.2 
sp.  gr.  When  solution  is  complete,  add  nitric  acid  drop  by  drop 
until  the  iron  is  oxidized;  5  c.c.  of  nitric  acid  1.2  sp.  gr.  is 
generally  sufficient. 

Boil  to  remove  nitrous  fumes  and  add  hot  water,  to  bring  the 
volume  to  150  c.c. ;  add  from  a  pipette,  5  c.c.  of  a  saturated  solu- 
tion of  potassium  permanganate  and  boil  briskly  for  15  to  20 
minutes;  remove  from  the  plate,  wash  down  the  sides  of  the 
beaker  to  remove  all  permanganate,  and  add  25  c.c.  strong 
ammonia  down  the  side  of  the  beaker ;  shake  well  and  replace 
on  the  cooler  part  of  the  plate,  to  avoid  "bumping,"  of  which 
there  is  some  danger  if  the  heat  be  raised  too  rapidly.  Shake 
occasionally  and  digest  for  about  15  minutes,  or  until  the  per- 
manganate is  all  decomposed,  then  add  cautiously  20  c.c.  dilute 
sulphuric  acid  1.58  sp.  gr.  and  bring  gently  to  boiling.  Cool  the 
solution  and  pour  into  a  graduated  250  c.c.  flask.  Make  up  to 
mark  with  cold  water,  and  mix  well  by  pouring  into  a  dry 
beaker,  back  and  forth  a  few  times.  Allow  to  settle  and  filter 
through  superposed  funnels,  with  close,  hard,  dry  filters,  into 
a  dry  beaker ;  measure  off  200  c.c.  (equal  to  I  gramme  sample) 
of  the  clear  filtrate,  and  titrate  by  adding  a  known  excess  of 
ferrous  sulphate,  and  determining  the  excess  by  standard  per- 
manganate. 

*  The  Iron  Age,  vol.  Hi.  p.  153. 


DETERMINATION  OF  ARSENIC. 


'95 


FIG.  86. 


DETERMINATION    OF   ARSENIC. 

By  Distillation. 

Lundin  *  has  suggested  the  following  method  of  determining 
arsenic,  which  gives  very  good  results:  Dissolve  10  grammes  of 
drillings  in  a  large  beaker  in  HNO3,  1.2  sp.  gr.,  transfer  the  solu- 
tion to  a  platinum  or  porcelain  dish,  add  50  c.c.  H2SO4,  and  evap- 
orate down  until  copious  fumes  of  sulphuric  acid  are  given  off. 
Cool  the  dish,  add  50  c.c.  of 
water,  and  evaporate  again  until 
the  excess  of  H2SO4  is  driven 
off,  and  the  ferric  sulphate  is  so 
dry  that  it  can  be  readily  trans- 
ferred to  a  flask  of  about  500 
c.c.  capacity.  Add  to  the  mass 
in  the  flask  1 5  grammes  finely- 
powdered  ferrous  sulphate, 
pour  in  150  c.c.  strong  HC1, 
and  close  the  flask  with  a 
stopper  carrying  a  tube  bent 
twice  at  right  angles  and  con- 
nected by  a  rubber  tube  with  a 
50  c.c.  pipette,  the  point  of  which  dips  about  y2  inch  (12  mm.) 
into  300  c.c.  of  water  in  a  beaker,  as  shown  in  Fig.  86.  Heat  the 
liquid  in  the  flask  gradually  until  it  boils,  and  continue  the  dis- 
tillation until  the  wide  part  of  the  burette  becomes  heated.  The 
arsenic  acid  in  the  solution  is  reduced  by  the  ferrous  sulphate, 
and,  in  the  strong  hydrochloric  acid  solution,  is  distilled  over  as 
AsCl3.  Remove  the  light,  disconnect  the  pipette,  heat  the  solution 
in  the  beaker  to  about  70°  C,  and  pass  a  rapid  current  of  H2S 
through  it  until  it  is  completely  saturated.  Remove  the  excess 
of  H2S  by  a  current  of  CO2,  and  when  the  solution  smells  very 


Reduction 

to 


*  Jern-Kontorets  Annaler,  1883,  p.  360;  Chem.  News,  li.  115. 


j^6  ANAL  YSIS   OF  IRON  AND   STEEL. 

faintly  of  H2S,  filter  off  the  yellow  precipitate  of  As2S3  in  a  Gooch 
crucible4  or  on  a  counterpoised  filter,*  wash  with  water,  then  with 
alcohol,  then  with  pure  disulphide  of  carbon,  dry  at  100°  C.,  and 
weigh  as  As2S3,  which  contains  60.93  per  cent,  of  As. 

Or,  after  filtering  the  precipitate  on  the  felt  in  a  Gooch  crucible, 
transfer  the  precipitate  and  felt  to  a  small  beaker,  add  a  little 
fuming  nitric  acid,  and,  when  action  has  nearly  ceased,  heat 
gently  until  the  sulphur  is  dissolved,  dilute,  filter,  and  evaporate 
Determining  down  to  about  io  c.c.  Add  5  c.c.  of  magnesium  mixture  and 
/^  the  volume  of  the  solution  NH4HO.  Stir  the  solution  vigor- 
ously from  time  to  time,  keeping  it  cool  by  immersing  the  beaker 
in  ice-water,  and  allow  it  to  stand  twelve  hours.  Filter  on  a 
Gooch  crucible,  wash  the  precipitate  of  Mg2(NH4)2As2O8  -f-  Aq 
with  the  ammonia  water  containing  nitrate  of  ammonium,  used 
for  washing  the  Mg2(NH4)2P2O8  (page  85),  dry  at  103°  C.  for 
half  an  hour,  then  increase  the  heat  very  gradually  to  redness, 
and  ignite  strongly  for  a  few  minutes.  Weigh  as  Mg2As2O7, 
which  contains  48.30  per  cent,  of  As. 


DETERMINATION    OF   ANTIMONY. 

Antimony  is  a  very  rare  constituent  of  iron  or  steel,  but 
very  minute  amounts  have  been  found  in  Spiegel.  To  deter- 
mine antimony,  treat  io  grammes  of  the  drillings  as  directed 
for  the  determination  of  arsenic  by  precipitation  with  H2S,  page 
1 88.  Evaporate  off  the  excess  of  NH4HO  from  the  filtrate  from 
the  Mg2(NH4)2As2O8  -f  Aq,  add  a  slight  excess  of  HC1,  dilute 
to  about  300  c.c.  with  water,  and  pass  a  current  of  H2S  through 
the  solution.  Expel  the  excess  of  H2S  by  a  current  of  CO2, 
filter  on  a  very  small  ashless  filter,  or  on  a  disk  of  paper  on 
the  bottom  of  a  Gooch  crucible,  wash  with  water,  and  dry  the 
precipitate  and  filter.  Separate  the  precipitate,  and  treat  the  fil- 
ter in  a  small  weighed  porcelain  crucible  with  fuming  HNO3. 

*  See  page  27. 


DETERMINATION  OF  TIN. 

When  it  is  dissolved,  evaporate  down,  add  more  HNO3  if  neces- 
sary, evaporate  to  dryness,  and  heat  to  destroy  the  organic  mat- 
ter. When  the  residue  in  the  crucible  is  quite  white,  allow  it 
to  cool,  add  the  precipitate,  and  treat  it  with  fuming  HNO3, 
evaporate  to  dryness,  and  finally  ignite  to  drive  off  the  sul- 
phuric acid  formed,  cool,  and  weigh  as  Sb2O4,  which  contains 
78.95  per  cent.  Sb.  When  tin  is  present,  and  the  arsenic  has  separation 
been  precipitated  from  a  sulphide  of  ammonium  solution,*  acid- 
ulate the  filtrate  from  the 'precipitate  of  Mg2(NH4)2As2O8 -{- Aq 
with  HC1,  and  when  the  solution  smells  but  faintly  of  H2S,  fil- 
ter on  a  small  ashless  filter,  wash  with  water,  alcohol,  and  finally 
with  disulphide  of  carbon,  dry  the  precipitate  and  filter,  and 
treat  them  with  fuming  HNO3,  evaporate  down,  but  not  to  dry- 
ness,  add  an  excess  of  dry  Na2CO3,  transfer  the  mass  to  a  silver 
crucible,  add  some  pure  fused  NaHO,  and  fuse  the  whole  for 
some  minutes.  Allow  the  crucible  to  cool,  dissolve  the  fused 
mass  in  water,  transfer  it  to  a  beaker,  and  add  %  the  volume 
of  alcohol,  .83  sp.  gr.  Stir  several  times,  and  allow  the  precipi- 
tate of  metantimonate  of  sodium  to  settle,  filter,  and  wash  with 
a  solution  consisting  of  equal  volumes  of  alcohol  and  water  con- 
taining a  little  Na2CO3  solution.  The  filtrate  contains  the  tin,  or 
tin  and  arsenic.  Dissolve  the  precipitate  of  metantimonate  of 
sodium  on  the  filter  in  HC1  containing  tartaric  acid,  allow  the  so- 
lution and  washings  to  run  into  a  small  beaker,  dilute  to  about 
300  c.c.,  and  precipitate  the  sulphide  of  antimony  by  H2S.  Fil- 
ter off,  and  determine  the  antimony  as  Sb2O4  as  above  directed. 


DETERMINATION    OF    TIN. 

Tin  is  a  most  unusual  constituent  of  steel  or  iron,  but   has 
been  found  in  the  former  in  cases  where  scrap  from  tinned  iron, 

*  The   precipitated  sulphides   from   acidulated  KHS  solution   may  be  treated 
directly  in  this  way  without  precipitating  the  arsenic  as  Mg2(NH4)2As2O8  +  Aq. 


jgg  ANALYSIS   OF  IRON  AND   STEEL. 

from  which  the  tin  has  been  removed  by  a  chemical  process, 
has  been  melted  in  the  open-hearth  furnace  as  a  portion  of.  the 
charge.  Proceed  as  in  the  determination  of  antimony,  until  the 
sulphides  from  the  acidulation  of  the  KHS  solution  have  been 
filtered  on  a  small  ashless  filter  and  washed  thoroughly  with  a 
solution  of  acetate  of  ammonium  made  slightly  acid  with  acetic 
acid.  It  is  not  possible  to  wash  the  precipitate  with  water,  as 
the  sulphide  of  tin  has  a  strong  tendency,  under  these  circum- 
stances, to  pass  through  the  filter.  Dry  the  precipitate  and  filter, 
transfer  the  precipitate  to  a  weighed  porcelain  crucible,  burn  the 
filter,  and  add  its  ash  to  the  precipitate,  add  a  little  sulphur, 
ignition  m  and  ignite  in  a  current  of  H2S,  as  directed  for  the  determina- 

HgS  vola-        ...  .-,  .  .  ... 

tion  of  manganese  as  MnS,  page  114.  Any  arsenic  present  will 
be  volatilized,  but  it  is  not  possible  to  weigh  the  tin  as  sulphide, 
as  its  composition  is  not  constant.  Heat  the  crucible  carefully, 
and  roast  the  precipitate  with  access  of  air,  heat  it  strongly  two 
or  three  times  with  carbonate  of  ammonium  to  volatilize  any 
sulphuric  acid  that  may  have  been  formed,  cool,  and  weigh  as 
SnO2,  which  contains  78.81  per  cent.  Sn. 


DETERMINATION   OF    TUNGSTEN. 

Dissolve  i  to  10  grammes  of  the  drillings  in  HNO3,  1.2  sp.  gr., 
evaporate  to  dryness  in  the  air-bath,  redissolve  in  HC1,  dilute 
slightly,  and  boil  for  some  time.  The  tungstic  acid  is  deposited 
as  a  yellowish  powder.  Dilute,  filter,  wash  with  hot  water  con- 
taining a  little  HC1,  and  finally  with  alcohol  and  water.  The  pre- 
cipitate consists  of  WO3  mixed  with  more  or  less  SiO2,  graphite, 
and  perhaps  a  little  Fe2O3,  TiO2,  etc.  Dry  and  ignite  the  filter 
and  precipitate,  and  burn  off  the  carbon.  Allow  the  crucible  to 
cool,  moisten  the  precipitate  with  water,  add  a  little  H2SO4  and 
an  excess  of  HFL  Evaporate  to  dryness  under  a  hood,  and 
ignite  to  drive  off  the  H2SO4.  Fuse  the  residue  with  5  times 


a- 

tion  as 
mercurous 


DETERMINATION  OF   TUNGSTEN. 

its  weight  of  Na2CO3,  allow  it  to  cool,  dissolve  in  water,  filter 
from  any  insoluble  matter,  and  wash  with  water  containing  a 
little  Na2CO3.  The  filtrate  contains  all  the  tungsten,  as  tungstate 
of  sodium.  Nearly  neutralize  with  HNO3,  and  boil  off  the  CO2, 
allow  the  solution  to  cool  slightly,  and  add  a  faint  but  distinct 
excess  of  HNO3.  Add  an  excess  of  mercurous  nitrate,*  and 
then  mercuric  oxide  diffused  in  water,*  until  the  free  acid  is  all 
neutralized.  The  tungsten  is  all  precipitated  as  mercurous  tung-  Precipit 
state,  and  can  be  washed  perfectly  free  from  all  sodium  salts  with 
hot  water.  Allow  the  precipitate  to  settle,  filter  on  an  ashless  tungstate. 
filter,  wash  with  hot  water,  and  dry  the  filter  and  precipitate. 
Separate  the  precipitate  from  the  filter,  burn  the  filter  in  a  plat- 
inum crucible,  add  the  precipitate,  and  heat  it  under  a  hood  with 
a  good  draft,  increasing  the  heat  gradually  to  a  bright  red.  The 
mercury  volatilizes,  and  there  remains  only  WO3.  Cool,  and 
weigh  as  WO3,  which  contains  79.31  per  cent,  of  W. 

Rapid  Method  for  Tungsten. 

A  rapid  method  for  the  determination  of  tungsten  in  high 
tungsten  steels  and  one  that  gives  results  sufficiently  accurate 
for  ordinary  work  is  as  follows : 

Treat  one  gramme  of  the  steel  in  a  No.  3  Griffin's  beaker 
with  25  c.c.  of  aqua  regia,  evaporate  to  dryness,  redissolve  in  10 
c.c.  strong  hydrochloric  acid,  add  I  or  2  c.c.  of  strong  nitric  acid, 
heat  for  a  few  minutes,  dilute  with  hot  water  to  100  c.c.,  and 
boil  for  ten  minutes.  Filter,  wash  with  water  containing  a  little 
hydrochloric  acid,  and  ignite.  Treat  the  precipitate  in  the 
crucible  with  a  few  drops  of  sulphuric  acid  and  some  hydro- 
fluoric acid,  evaporate  to  dryness,  ignite,  and  weigh.  Fuse  the 
precipitate  with  a  little  sodium  carbonate,  dissolve  in  hot  water, 
filter  off  the  ferric  oxide,  wash  it  well  with  hot  water,  return  it 
to  the  crucible,  ignite,  and  weigh.  The  difference  between  the 
two  weights  is  WO3. 

*  See  page  56. 


2QO  ANALYSIS   OF  IRON  AND   STEEL. 

DETERMINATION    OF    VANADIUM. 

Vanadium  is  occasionally  found  in  pig-iron,  and  may  be  deter- 
mined with  great  accuracy  by  the  following  method  :  Treat  5 
grammes  of  the  drillings  with  50  c.c.  HNO3,  1.2  sp.  gr.,  in  a  No.  4 
beaker.  When  all  action  has  ceased,  transfer  the  liquid  to  a 
porcelain  dish,  evaporate  to  dryness,  and  heat  at  a  gradually  in- 
creasing temperature  over  a  Bunsen  burner  until  the  nitrates  are 
nearly  all  decomposed  and  the  mass  separates  easily  from  the 
bottom  and  sides  of  the  dish.  Transfer  the  cooled  mass  to  a  por- 
celain or  agate  mortar,  and  grind  it  thoroughly  with  30  grammes 
of  dry  Na2CO3  and  3  grammes  of  NaNO3.  Transfer  to  a  large 
platinum  crucible,  and  fuse  well  for  about  an  hour  at  a  high  tem- 
perature. Run  the  fused  mass  well  up  on  the  sides  of  the  crucible, 
allow  it  to  cool,  dissolve  in  hot  water,  and  filter.  Dilute  the  filtrate 
to  about  600  c.c.,  and  add  nitric  acid  carefully  to  get  rid  of  the  car- 
bonic acid.  Boil  off  the  latter,  but  be  careful  to  keep  the  solu- 
tion always  slightly  alkaline.  Filter,  and  to  the  filtrate  add  a  few 
drops  of  nitric  acid  to  make  it  faintly  acid,  when  the  appearance 

indication  of  a  yellowish  coloration  is  an  indication  of  the  presence  of  vanadic 
acid.  Add  to  the  solution  a  few  c.c.  of  mercurous  nitrate,*  and 

Predpita-  then  an  excess  of  mercuric  oxide  in  water,*  to  render  the  solution 
mercurous  ncutralf  and  insure  the  complete  precipitation  of  all  the  mer- 
vanadate.  curous  vanadate.  With  the  mercurous  vanadate  are  precipitated 
also  all  the  phosphoric,  chromic,  tungstic,  and  molybdic  acids  as 
mercurous  salts.  Heat  to  boiling,  filter,  and  wash  the  precipitate. 
Dry  it,  separate  the  paper,  burn  it  in  a  platinum  crucible,  add  the 
precipitate,  heat  carefully  to  expel  the  mercury,  and  finally  heat 
to  full  redness.  Fuse  the  brownish-red  mass  remaining  in  the 
crucible  with  a  small  amount  of  Na2CO3  and  a  pinch  of  NaNO3, 
dissolve  the  cooled  mass  in  a  small  amount  of  water,  and  filter 
into  a  small  beaker.  Add  to  the  solution  pure  chloride  of  ammo- 
nium in  excess  (about  3.5  grammes  to  each  10  c.c.  of  solution), 

*  See  page  56.  f  Am.  Chem.  Jour.,  v.  373. 


DETERMINATION  OF  NITROGEN.  2OI 

and  allow  it  to  stand  for  some  time,  stirring  occasionally.     Vana-   Predpita- 
date  of  ammonium,  insoluble  in  a  saturated  solution  of  chloride     vanadate 
of  ammonium,  separates  out  as  a  white  powder.     It  is  necessary     m0nium. 
to  keep  the  solution  decidedly  alkaline,  and  a  drop  or  two  of  am-   Precautions, 
monia  must  be  added  from  time  to  time.     The  appearance  of  the 
faintest  yellowish  tint  to  the  solution  is  evidence  that  the  solution 
has  become  slightly  acid,  and  this  must  be  corrected  or  the  result 
will  be  too  low.     Filter  on  a  small  ashless  filter,  wash  first  with  a 
saturated  solution  of  chloride  of  ammonium  containing  a  drop  or 
two  of  ammonia,  and  then  with  alcohol.     Dry,  ignite,  moisten  with 
a  drop  or  two  of  nitric  acid,  ignite,  and  weigh  as  V2O5,  which 
contains  56.22  per  cent,  of  vanadium. 


DETERMINATION   OF  NITROGEN. 

This  method  is  based  on  the  reaction  by  which  the  nitrogen 
in  iron  or  steel  is  converted  into  ammonia  by  HC1  during  the 
solution  of  the  steel  in  this  reagent. 

It  was  first  published  by  A.  H.  Allen,*  with  many  interest- 
ing details  and  results.  The  modifications  of  the  method  as 
described  by  Mr.  Allen  are  by  Prof.  J.  W.  Langley,f  of  Pitts- 
burg,  and  consist  essentially  in  the  use  of  caustic  soda  freed  from 
nitrates  and  nitrites  by  the  copper-zinc  couple  and  subsequent 
distillation  of  all  ammonia  formed,  and  in  a  few  details  of 
manipulation. 

The  reagents  required  are: 

Hydrochloric  Acid  of  i.i  sp.  gr.,  free  from  Ammonia,  which  pure  HO. 
may  be  prepared  by  distilling  pure  hydrochloric  acid  gas  into 
distilled  water  free  from  ammonia.     To  do  this,  take  a  large  flask 
fitted  with  a   rubber   stopper   carrying  a   separatory  funnel-tube 
and    an    evolution-tube,   fill    it    half-full  of  strong    hydrochloric 

*  Chem.  News,  xli.  231.  •}•  Communicated  to  the  author. 


2Q2  ANALYSIS   OF  IRON  AND   STEEL. 

acid,  connect  the  evolution-tube  with  a  wash-bottle  connected 
with  a  bottle  containing  the  distilled  water.  Admit  strong  sul- 
phuric acid  free  from  nitrous  acid  to  the  flask  through  the  funnel- 
tube,  apply  heat  as  required,  and  distil  the  gas  into  the  prepared 
water. 

Test  the  acid  by  admitting  some  of  it  into  the  distilling  appa- 
ratus, described  farther  on,  and  distilling  it  from  an  excess  of  pure 
caustic  soda,  or  determine  the  amount  of  ammonia  in  a  portion 
of  hydrochloric  acid  of  i.i  sp.  gr.,  and  use  the  amount  found 
as  a  correction. 

Caustic  Solution  of  Caustic  Soda,  made   by   dissolving   300   grammes 

of  fused  caustic  soda  in  500  c.c.  of  water,  and  digesting  it  for 
twenty-four  hours  at  50°  C.  on  a  copper-zinc  couple,  made,  as 
described  by  Gladstone  &  Tribe,  as  follows  :  Place  25-30  grammes 
of  thin  sheet  zinc  in  a  flask  and  cover  with  a  moderately-con- 
centrated, slightly  warm  solution  of  sulphate  of  copper.  A  thick 
spongy  coating  of  copper  will  be  deposited  on  the  zinc.  Pour 
off  the  solution  in  about  ten  minutes  and  wash  thoroughly  with 
cold  distilled  water. 

Nessier  Nessler  Reagent.     Dissolve    35   grammes    of  iodide  of  potas- 

sium in  a  small  quantity  of  distilled  water,  and  add  a  strong 
solution  of  bichloride  of  mercury  little  by  little,  shaking  after 
each  addition,  until  the  red  precipitate  formed  dissolves.  Finally 
the  precipitate  formed  will  fail  to  dissolve,  then  stop  the  addition 
of  the  mercury  salt  and  filter.  Add  to  the  filtrate  120  grammes 
of  caustic  soda  dissolved  in  a  small  amount  of  water,  and  di- 
lute until  the  entire  solution  measures  I  litre.  Add  to  this  5 
c.c.  of  saturated  aqueous  solution  of  bichloride  of  mercury,  mix 
thoroughly,  allow  the  precipitate  formed  to  settle,  and  decant 
or  siphon  off  the  clear  liquid  into  a  glass-stoppered  bottle. 

standard  Standard    Ammonia    Solution.      Dissolve   0.0382    gramme   of 

solution      chloride  of  ammonium  in   I   litre  of  water.     One  c.c.  of  this  so- 
lution will  equal  O.OI   milligramme  of  nitrogen. 

Distilled   Water  free  from   Ammonia.      If   the    ordinary    dis- 


DETERMINATION  OF  NITROGEN.  203 

tilled  water  contains  ammonia,  redistil  it,  reject  the  first  portions  Ammonia- 

free 

coming   over,  and    use   the   subsequent   portions,  which  will   be     distnied 
found  free  from  ammonia.     Several  glass  cylinders  of  colorless 
glass  of  about   1 60  c.c.  capacity  are  also  required. 

The  •  best  form   of  distilling  apparatus  consists  of  an  Erlen-  Distn- 
meyer  flask  of  about   1500  c.c.  capacity,  with  a  rubber  stopper,      paratus. 
carrying  a  separatory  funnel-tube  and  an  evolution-tube,  the  lat- 
ter connected  with  a  condensing-tube  through  which  a  constant 
stream   of  cold  water  runs.      The   inside  tube,  where  it   issues 
from  the  condenser,  should  be  sufficiently  high  to  dip  into  one 
of  the  glass  cylinders  placed  on  the  working-table. 

The  determination  of  nitrogen  is  made  as  follows :  Place  30  Details 
c.c.  of  the  caustic  soda,  which  has  been  treated  with  the  cop-  method 
per-zinc  couple,  in  the  Erlenmeyer  flask,  add  500  c.c.  of  water, 
and  distil  until  the  distillate  gives  no  reaction  with  the  Nessler 
reagent.  While  this  part  of  the  operation  is  in  progress,  dissolve 
3  grammes  of  the  carefully-washed  drillings  in  30  c.c.  of  the 
prepared  hydrochloric  acid,  using  heat  if  necessary.  Transfer 
the  solution  to  the  bulb  of  the  separatory  funnel-tube,  and  when 
the  soda  solution  is  free  from  ammonia  drop  the  ferrous  chlo- 
ride solution  into  the  boiling  solution  in  the  flask,  very  slowly. 
The  ferrous  hydrate  formed  is  apt  to  stick  to  the  bottom  and 
sides  of  the  flask  and  cause  it  to  break.  When  about  50  c.c. 
of  water  has  been  collected  in  the  cylinder,  remove  it  and  sub- 
stitute another  cylinder.  Dilute  the  distillate  in  the  cylinder  to 
100  c.c.  with  the  special  distilled  water,  and  add  \y2  c.c.  of 
Nessler  reagent.  Take  another  cylinder,  pour  into  it  100  c.c. 
of  the  special  distilled  water,  add  I  c.c.  of  the  chloride  of  am- 
monium solution  and  I  j£  c.c.  of  the  Nessler  reagent.  Compare 
the  colors  in  the  two  cylinders,  and  add  ammonia  solution  to  the 
contents  of  the  latter  cylinder  until  the  colors  of  the  solutions 
in  the  two  cylinders  correspond  after  standing  about  ten  minutes. 
When  about  100  c.c.  has  distilled  into  the  second  cylinder,  re- 
place it  and  test  it  as  before.  Continue  the  distillation  until 


2O4  ANALYSIS   OF  IRON  AND   STEEL. 

the  water  comes  over  free  from  ammonia,  then  add  together 
the  number  of  c.c.  of  ammonia  solution  used,  divide  the  sum 
by  three,  and  each  o.oi  milligramme  will  be  o.ooi  per  cent,  of 
nitrogen  in  the  steel. 


DETERMINATION   OF    IRON. 

The  combined  carbon  in  steel  and  iron  interferes  with  a  direct 
determination  of  the  amount  of  metallic  iron  by  solution  of  the 
drillings  in  hydrochloric  or  sulphuric  acid  and  direct  titration. 
It  is  always  necessary  to  oxidize  the  iron  and  carbonaceous  matter 
in  the  solution,  and  the  process  may  be  carried  out  as  follows: 

By  solution.  Dissolve  .5  gramme  of  the  drillings  in  a  small  flask,  as  described 
for  the  determination  of  iron  in  iron  ores,  in  HC1,  add  KC1O3  in 
small  crystals  until  the  iron  is  all  oxidized  and  an  excess  of  KC1O3 
is  present,  boil  until  all  the  yellow  fumes  have  disappeared,  and 
then  proceed  as  in  the  determination  of  iron  in  iron  ores,  page 
207.  Instead  of  chlorate  of  potassium,  permanganate  of  potassium 
or  chromic  acid  may  be  used  to  oxidize  the  iron  and  destroy 
the  carbonaceous  matter.  In  pig-irons  the  most  satisfactory 

By  fusion,  method  is  to  fuse  .5  gramme  of  the  borings  in  a  large  platinum 
crucible  with  10  grammes  Na2CO3  and  2  grammes  KNO3,  dissolve 
in  hot  water,  transfer  to  a  small  beaker,  allow  the  ferric  oxide  to 
settle,  decant  on  a  small  filter,  and  wash  several  times  by  decanta- 
tion.  After  the  last  decantation,  remove  the  beaker  containing  the 
filtrate  and  place  the  beaker  containing  the  ferric  oxide  under  the 
funnel.  Dissolve  any  adhering  oxide  in  the  crucible  with  HC1, 
dilute  slightly,  and  pour  it  on  the  filter  to  dissolve  the  small 
amount  of  oxide,  allowing  the  solution  to  run  into  the  beaker. 
Wash  the  filter  if  necessary,  add  more  HC1  to  the  solution  in  the 
beaker,  evaporate  down,  transfer  to  a  small  flask,  deoxidize,  and 
titrate  as  before.  In  the  case  of  puddled  iron,  it  is  necessary  to 
subtract  the  iron  in  the  "  slag  and  oxides"  from  the  total  iron  ob- 
tained as  above  to  get  the  amount  of  metallic  iron  in  the  sample. 


METHODS  FOR  THE  ANALYSIS 


OF 


IRON  ORES. 


A   FEW   words   in   regard   to   the  proper   method   of  taking  Method  of 
samples  of  iron  ores  may  not  be  amiss,  for  unless  the   sample     iron  ores, 
truly  represents  the  lot  from  which  it' is  taken,  the  subsequent 
work  of  the  analyst  is  useless,  if  not  misleading. 

In  drawing  a  sample,  note  carefully  the  relative  amounts  of 
fine  ore  and  lumps  in  the  lot  to  be  sampled,  and  see  that  this 
proportion  be  observed  in  the  whole  amount  taken.  A  small 
trowel  may  be  used  for  taking  the  fine  ore,  and  only  about  a 
teaspoonful  should  be  picked  up  at  one  time.  In  taking  pieces 
from  the  lumps,  it  will  never  do  to  merely  chip  the  outside,  but 
each  lump  as  selected  should  be  broken  and  chippings  taken 
from  both  the  inside  and  the  outside,  and  no  piece  taken  should 
be  larger  than  a  cherry.  In  sampling  from  cars  or  wagons  these 
points  should  be  observed  in  each  car  or  wagon,  for  it  is  rarely 
the  case  that  the  ore  even  from  one  mine  is  so  uniform  as  to  render 
this  precaution  unnecessary.  In  some  cases  the  lumps  are  covered 
with  dirt  or  gangue,  making  the  outside  of  the  lump  poorer  in 
iron  than  the  inside,  and  on  the  other  hand  the  lumps  are  merely 
masses  of  dirt  coated  with  ore.  Then  the  fine  stuff  may  be  much 
richer  than  the  lumps,  or  it  may  be  merely  dirt  or  gangue,  while 
it  almost  always  contains  more  hygroscopic  water  than  the  lumps. 
The  sample  should  be  taken  in  tin  cans  with  close-fitting  lids,  Preserving 
and  the  amount  should  be  proportioned  to  the  size  of  the  lot 

sampled.     Two  pounds  to  ten  tons  is  a  good  rule  for  large  lots. 

205 


2O6 


ANALYSIS   OF  IRON  ORES. 


DETERMINATION    OF    HYGROSCOPIC   WATER. 

Break  the  sample  down  quickly  to  about  pea  size,  mix  thor- 
oughly in  a  large  glazed  earthenware  or  metal  dish,  and  weigh  out 
from  y2  to  I  kilo,  into  a  copper  box  about  4^  inches  (114  mm.) 
long,  3^  inches  (95  mm.)  wide,  and  ij^  inches  (38  mm.)  deep, 
and  dry  in  a  water-  or  air-bath  at  1 00°  C.  for  at  least  twelve  hours, 
or  until  it  ceases  to  lose  weight.  Fig.  87  shows  a  convenient  form 


FIG.  87. 


Device  for 
constant 
level. 


of  water-bath.  The  boxes  are  numbered,  and  each  one  is  pro- 
vided with  a  counterpoise  stamped  with  the  same  number  as  the 
box,  to  facilitate  the  weighing.  When  a  supply  of  water  is  not 
available  to  run  the  constant  level  shown  in  Fig.  87,  the  device, 
on  the  principle  of  Marriott's  flask,  as  shown  in  Fig.  78,  page  169, 


DETERMINATION  OF   TOTAL   IRON. 


207 


may  be  used.     The  position  of  the  end  b  of  the  tube  a  fixes  the 
level  of  the  water  in  the  bath. 

A  balance  sensitive  to  .1  gramme  is  sufficiently  accurate  for  Balance  for 
weighing  these  samples.     The  loss  of  weight  in  grammes  divided     samples. 
by  5,  when  j£  kilo,  of  ore  was  originally  used,  gives  the  percentage 
of  hygroscopic  water  in  the  sample.     Grind  the  dried  sample  very 
fine,  mix  it  well,  heat  as  much  of  it  as  may  be  required  for  the 
analysis,  in  the  water-bath,  and  put  it  while  still  hot  into  a  per- 
fectly dry,  glass-stoppered  bottle. 


DETERMINATION    OF    TOTAL    IRON. 

Very  few  iron   ores  are   completely  decomposed   by  hydro-  Residue 
chloric  acid,  the  insoluble  residue  usually  containing  more  or  less     faHca. 
iron,  as  silicate,  titaniferous  iron,  etc.     The  disregard  of  this  fact 
may  occasion    grave   errors  in   the   determination  of  iron,  and, 
unless  a  previous  examination  has  shown  the  absence  of  iron  in 
the  insoluble  residue,  it  is  best  to  proceed  as  follows :    Weigh   I   Treatment 
gramme  of  the  finely-ground  sample  into  a  No.  I  beaker,  add  10 
c.c.  HC1,  and  digest  it  on  the  sand-bath  until  the  residue  appears 
quite  white  and  flotant,  or  until  the  acid   appears  to  have  no 
further  action.     When  the  ore  contains  carbonaceous  matter,  add 
a  little  KC1O3.     Wash  off  the  watch-glass  with  a  fine  jet  of  water, 
remove  it,  and  evaporate  to  dryness  in  the  air-bath.     Redissolve 
in  about  5  c.c.  HC1,  dilute  with  10  c.c.  water,  allow  to  settle,  and 
decant  the  clear  liquid  into  a  flask  (B,  Fig.  89)  of  about  50  to  75 
c.c.  capacity.     Transfer  the  residue  to  a  small  filter,  fitted  in  a 
funnel  placed  in  the  neck  of  the  flask,  with  as  little  water  as  pos-  Treatment 
sible,  and  wash  with  cold  water  from  a  fine  jet.    Transfer  the  filter     of*? in' 

soluble 

to  a  small  platinum  crucible,  burn  it  off,  allow  the  crucible  to  cool,     residue 

by  H2S04 

and  pour  on  the  residue  20  or  30  drops  of  H2SO4  and  about  twice     and  HFI. 


2o8  ANALYSIS   OF  IRON  ORES. 

as  much  HF1.  Heat  carefully,  and,  if  the  residue  is  dissolved,  evap- 
orate off  the  HF1,  allow  the  liquid  to  cool,  and  dilute  slightly, 
when  it  will  be  ready  to  add  to  the  solution  in  the  flask,  which 
shall  have  been  deoxidized  in  the  mean  time  by  one  of  the 
methods  explained  farther  on. 

Occasionally  this  treatment  fails  to  decompose  the  insoluble 

residue,  in  which  case  it  is  necessary  to  heat  the  crucible  until 

the  greater  part  of  the  H2SO4  shall  have  been  driven  off;  then 

Treatment     add    about  .5    gramme    KHSO4,    and    heat    gradually    until    the 

with 

KHS04.  KHSO4  is  quite  liquid  and  fumes  of  SO3  are  given  off  whenever 
the  lid  of  the  crucible  is  raised.  When  all  the  black  specks  have 
disappeared,  allow  the  crucible  to  cool,  and  dissolve  the  salt  in 
the  crucible  with  hot  water  and  a  few  drops  of  HC1. 

Several  methods  are  used  for  the  deoxidation  of  the  solution 
of  ferric  chloride,  but  the  one  in  general  use  is  by  adding  metallic 
zinc  to  the  solution.  The  iron  is  deoxidized  according  to  the 
reaction  Fe2Cl6+  Zn  =  2FeCl2-f  ZnQ2,  while  the  excess  of  HC1 
is  decomposed  and  hydrogen  liberated,  2HC1+ Zn  =  ZnCl2-f  2H. 
As  all  zinc  contains  a  small  amount  of  iron,  the  amount  added  to 
the  solution  should  be  roughly  weighed.  Add  then  to  the  solu- 


metallic  tion  in  the  flask  3  grammes  of  granulated  zinc,*  and,  when  the 
evolution  of  hydrogen  has  somewhat  slackened,  heat  the  flask 
slightly.  The  neck  of  the  flask  is  closed  by  a  small  funnel,  which 
allows  the  hydrogen  to  escape  while  the  liquid  is  caught  on  the 
funnel  and  falls  back  into  the  flask.  It  sometimes  happens  as  the 
solution  becomes  neutralized  that  a  basic  salt  of  peroxide  of  iron 
is  thrown  down,  giving  the  solution  a  reddish  color ;  in  this  case 
add  a  few  drops  of  HC1,  and  when  the  solution  finally  becomes 

End  of  the  colorless  add  a  few  drops  more  of  HC1.  If  this  fails  to  produce  a 
yellowish  coloration,  the  solution  may  be  considered  deoxidized. 

Final  addi-  Pour  in  through  the  funnel  the  solution  of  the  residue  insoluble  in 
H2so4.  HC1,  and  add  gradually  a  mixture  of  10  c.c.  H2SO4  and  20  c.c. 

*  See  page  57. 


DETERMINATION  OF   TOTAL   IRON.  2OQ 

H2O.  This  addition  of  H2SO4  is  a  very  necessary  part  of  the 
operation,  for  it  not  only  serves  to  dissolve  the  remainder  of  the 
zinc  which  is  unacted  on  when  the  deoxidation  is  complete,  but  it 
supplies  the  proper  amount  of  sulphate  of  zinc  and  iron,  which 
makes  the  end  reaction  with  permanganate  of  potassium  as  sharp 
as  if  no  HC1  were  present  in  the  solution.  As  soon  as  all  the 
zinc  is  dissolved,  wash  down  the  funnel  inside  and  out  and  the 
neck  of  the  flask  with  a  fine  jet  of  water,  filling  the  flask  almost 
full,  cool  the  flask  in  water,  and  when  the  solution  is  quite  cold 
transfer  it  to  a  large  white  dish  of  about  1500  c.c.  capacity  (see  A, 
Fig.  89,  page  214).  Wash  the  flask  and  funnel  well  with  cold 
water,  pour  the  rinsing  into  the  dish,  and  make  the  solution  up  to 
about  1000  c.c.  Run  in  from  a  burette  a  standard  solution  of  Titratkm  by 

£  perman- 

permanganate  of  potassium  (Marguerite's  method),  the  value  of  ganate 
which  has  been  carefully  determined  by  one  of  the  methods  de- 
scribed farther  on.  At  first  the  color  of  the  permanganate  is 
destroyed  almost  as  soon  as  it  touches  the  liquid  in  the  dish,  which 
should  be  stirred  carefully  with  a  glass  rod.  The  permanganate 
should  be  added  more  and  more  slowly  until  towards  the  end  of 
the  operation  it  is  added  only  drop  by  drop.  The  liquid  in  the 
dish  gradually  assumes  a  yellowish  tint,  which  is  deeper  the 
larger  the  amount  of  iron  jn  the  ore.  Finally  a  drop  of  the  per- 
manganate seems  to  destroy  the  yellow  color,  and  the  next  drop 
gives  the  liquid  a  very  faint  pink  tinge.  This  is  the  end  of  the 
reaction.  Take  the  reading  of  the  burette,  and  then  add  another 
drop,  which  will  cause  the  solution  to  become  decidedly  pink  in 
color.  The  number  of  c.c.  of  the  standard  solution  used  when 
the  reading  was  taken,  less  a  small  correction  for  the  zinc,  etc., 
noted  farther  on,  multiplied  by  the  value  of  I  c.c.,  gives  the 
amount  of  metallic  iron  in  the  ore. 

The  reductor,  Fig.  88,  is  also  useful  for  reducing  ferric  salts  to  Jones's 
ferrous ;  the  only  disadvantage  is  that  it  seems  necessary  to  have 
the  iron  present  as  sulphate,  which  necessitates  evaporating  off  the 
hydrochloric  acid  used  in  dissolving  ores.     The  description  of  the 

14 


210 


ANALYSIS   OF  IRON  OKES. 


reductor  and  the  method  of  using  it  in  iron  determinations  is  as 
follows :  * 

The  conditions  essential  to  the  accurate  determination  of 
iron  by  this  method  are :  That  the  iron  must  be  in  the  state 
of  ferric  sulphate ;  that  the  solution  of  ferric  sulphate  must  be 
dilute;  that  the  least  traces  of  hydrochloric  and  nitric  acids 
must  be  absent.  There  should  not  be  over  50  c.c.  sulphuric 
acid,  1.32  sp.  gr.,  in  300  c.c.  of  the  ferric  solution  ready  for  re- 
duction. 

For  iron  ores,  and  in  almost  all  cases,  this  ordinarily  pre- 
sents no  difficulties.  If  the  solution  is  in  strong  sulphuric  acid, 
it  must  be  reduced  in  bulk,  or  diluted  to  such  an  extent  as  to 
avoid  violent  action  in  contact  with  zinc.  The  volume  of  the 
solution  should  not  exceed  350  c.c. 

Preparing  The  reductor  should  now  be  filled  with  zinc  and  washed  as 

ductor.  required.  If  there  is  still  enough  zinc  remaining  in  the  tube 
from  previous  reductions,  a  single  washing  will  usually  suffice. 
The  ferric  solution  is  now  brought  to  the  reductor  and  trans- 
ferred to  one  or  both  of  the  cups  A  and  B,  washing  out  the 
beaker  or  flask  three  or  four  times  with  water. 

Details  of  The  stopcock  G  of  the  reductor  is  opened,  and  the  two-way 

stopcock  C  is  set  to  discharge  the  solution,  which  is  then  filtered 
through  the  zinc.  The  cup  is  then  rinsed  out  five  times  with 
water  as  described.  The  stopcock  G  is  then  closed  to  relieve 
the  pressure,  and  the  flask  F  is  detached.  The  solution  has 
now  a  volume  of  about  400  to  500  c.c.  In  this  manner  a  solu- 
tion of  ferric  sulphate  is  instantaneously  and  completely  reduced 
in  two  minutes.  The  burette  is  now  filled  to  the  zero  mark  as 
described,  and  the  solution  is  titrated  in  the  flask  direct. 

A  little  practice  will  enable  the  operator  to  give  a  continuous 
circular  motion  to  the  flask  held  in  the  right  hand,  with  the  left 
hand  in  control  of  the  flow  of  the  permanganate  from  the  burette. 

*  Prepared  by  Mr.  Clemens  Jones  for   this  volume. 


DETERMINATION  OF   TOTAL   IRON. 


211 


The  average  time  by  this  means  for  the  reduction  and  accu- 
rate  titration  of  a  ferric  solution  is  four   minutes.     The   burette   Description 
B  (50  c.c.  to  ^  c.c.),  shown  in  Fig.  88,  consists  of  the   gradu- 

FIG.  88. 

A 


ated  glass  tube  proper,  and  an  arm,  E,  fused  to  it,  below  the 
50  c.c.  mark.  At  its  top  are  rubber  connections  with  the  blast- 
aspirator,  shown  in  the  cut.  By  means  of  the  stopcock  D  con- 


ANALYSIS   OF  IRON  ORES. 

nection  through  E  is  established  with  the  glass  reservoir  F. 
The  burette  is  clamped  securely  to  a  slide,  C,  which  is  coun- 
terpoised, and  moves  freely  on  guides  between  two  parallel  sides, 
L,  L,  suitably  mounted  in  a  frame,  and  through  their  whole 
length. 

Back  of  the  burette  a  porcelain  scale  may  be  fixed,  graduated 
to  correspond  with  it,  and  secured  to  the  slide,  in  front  of  which 
the  burette  may  be  adjusted.  The  reservoir  F  is  suspended  in 
a  shelf  placed  within  the  frame,  and  is  introduced  into  the  side- 
door  K,  shown  open,  and  is  then  encased  in  a  box,  which  has 
an  annular  hole  in  the  top  to  admit  the  prong  of  the  tube  E, 
the  slide  C  being  previously  raised.  The  reservoir  is  so  placed 
that  when  the  slide  is  at  the  lowest  point  the  inlet-prong  has 
a  safe  margin  from  the  bottom. 

If  a  float  is  used,  it  remains  in  the  burette  permanently,  and 
is  caught  on  a  stage  of  fine  platinum  wire  supported  by  a  spiral, 
when  it  descends  within  one-half  inch  of  the  inlet-tube.  In 
Reservoir  operation,  the  reservoir  F,  containing  about  two  litres,  is  filled 
with  the  solution  of  permanganate  and  placed  in  position ;  the 
slide  C  is  lowered  until  the  zero  marks  are  brought  in  the  di- 
rect line  of  vision;  blast  is  admitted  to  the  aspirator  by  the 
brass  valve  V,  and  the  suction  produced  is  communicated  to  the 
burette,  both  stopcocks,  H  and  D,  being  closed. 

When  the  float  is  used,  the  stopcock  H  is  first  opened,  the 
suction  lifting  the  float  to  the  zero  mark  in  the  burette.  Stop- 
cock H  is  then  closed,  and,  while  the  float  slowly  descends,  stop- 
cock D  is  opened,  admitting  the  permanganate  solution  and 
allowing  the  float  to  sink  without  enclosing  any  bubbles  of  air. 
The  burette  is  then  filled  exactly  to  the  zero  mark.  In  titration, 
the  blast  must,  of  course,  be  shut  off,  and  the  column  of  solution 
connected  with  the  outside  atmosphere  by  turning  a  suitably- 
arranged  stopcock  of  the  aspirator.  If  the  float  is  not  employed, 
stopcock  H  remains  closed,  and  by  opening  stopcock  D  the 
burette  is  filled  in  the  manner  described  above. 


manganate 
solution. 


DETERMINATION  OF  TOTAL   IRON. 
To  cleanse  the  burette,  allow  the  solution   partially  filling  it  Method  of 

„.  ,       TT     .         -  cleaning 

to  run  out.  Stopcock  H  is  then  closed,  suction  is  again  pro-  burette, 
duced  by  starting  the  aspirator  as  described,  and  a  beaker  of 
water  is  held  so  that  the  burette  tip  is  in  the  water.  On  open- 
ing the '  stopcock  H,  the  water  rises  in  the  burette.  This  is  then 
run  out  by  again  stopping  the  aspirator,  and  the  operation  is 
repeated  until  the  burette  is  perfectly  clean.  Should  the  burette 
require  further  cleansing,  hydrochloric  acid  may  be  used  in  the 
same  manner.  This  is  then  washed  out  with  water  as  before, 
and  the  burette  may  then  be  dried  in  a  few  minutes  by  turning 
on  the  blast  gently,  and  reversing  the  aspirator  by  simply  closing 
its  main  outlet  with  a  rubber  cap,  allowing  the  current  of  air  to 
pass  down  through  the  burette  and  out  through  the  open  stop- 
cock H.  By  closing  the  outside  doors  the  apparatus  is  protected 
from  light.  The  apparatus  is  always  ready  for  use.  Twenty  ac- 
curate titrations  can  be  easily  made  in  an  hour's  time. 

The  simple  form  of  reductor,  Fig.  52,  shown  on  page  96, 
may  be  used  for  deoxidizing  the  solution  of  the  ore  in  which  the 
iron  is  in  the  form  of  sulphate.  With  amalgamated  zinc  it  is  a 
most  excellent  and  rapid  device.  The  method  of  reduction  is 
given  on  page  98  in  the  description  of  the  method  of  standard- 
izing the  potassium  permanganate  solution. 

Another  form  of  burette  which  is  extremely  convenient  and  Another 

form  of 

has  the  great  advantage  of  dispensing  with  the  glass  stopcock,     burette; 
which  is  liable  to  stick  at  a  critical  moment,  or  break  without 
warning,  is  shown  in  Fig.  89. 

The  burette  is  attached  to  the  wooden  stand  by  bands  of 
German  silver  or  of  nickel.  The  top  of  the  burette  is  closed 
by  a  rubber  stopper  carrying  a  glass  tube  of  small  bore  con- 
nected by  rubber  tubing  with  a  small  glass  tube  attached  to  the 
back  of  the  burette-stand.  To  the  end  of  this  tube,  near  the 
base  of  the  burette-stand,  is  attached  a  short  piece  of  heavy- 
walled  gum  tubing,  a,  passing  under  a  compressor  fixed  to  the 
base  of  the  stand.  Fig.  90  shows  the  form  and  construction  of 


214 


ANALYSIS   OF  IRON  ORES. 


FIG.  89. 


the  clamp  or  compressor.  By  applying  suction  at  the  end  of 
the  tube  b  the  standard  solution  may  be  drawn  up  into  the 
burette  a  little  above  the  zero  mark,  and  the  compressor  closed 

down  on  the  tube  a, 
holding  the  liquid  in 
the  burette  until  the 
admission  of  air  through 
the  tube  a  allows  the 
liquid  to  flow  out  of 
the  burette.  The  entire 
practical  value  of  this 
burette  *  depends  on 
placing  a  drop  or  two 
of  water  in  the  tube  «, 
which,  flowing  to  the 
point  of  compression, 
not  only  closes  the  tube 
hermetically  when  the 
clamp  is  screwed  down, 


FIG.  90. 


Method  of      Dut  makes  it  possible,  by  a   slight  movement  of  the   clamp,  to 

controlling 

the  flow  of  admit  the  smallest  quantity  of  air  to  the  burette,  and  thus  to 
permit  the  liquid  to  flow  from  the  burette  at  any  desired  rate. 
The  flow  is  thus  controlled  by  the  left  hand  while  the  solution  in 
the  dish  is  stirred  with  the  right.  Towards  the  end  of  the  opera- 


The  suggestion  of  Mr.  Thos.  H.  Garrett,  of  Philadelphia 


DETERMINATION  OF   TOTAL   IRON.  215 

tion  a  single  drop  may  be  made  to  flow  from  the  burette,  when 
the  clamp  is  closed  (not  too  tightly),  by  compressing  the  tube  a 
at  the  point  c  with  the  thumb,  and  forcing  a  little  air  into  the 
burette.  Even  a  fraction  of  a  drop  may  be  obtained  by  touching 
the  point  of  the  burette  with  the  stirring-rod.  The  scale  shown 
in  the  sketch  is  fixed  on  the  wall,  so  that  the  eye  may  always  be 
kept  at  the  proper  level  in  taking  the  readings  of  the  burette. 

When  usiner  a  standard  solution  of  bichromate  of  potassium  Thration 

with  bi- 

(Penny's  method),  the  end  reaction  is  not  rendered  apparent  by  a  chromate 
change  in  the  color  of  the  solution,  but  the  presence  or  absence  sium. 
of  ferrous  salt  in  the  solution  is  determined  by  taking  a  drop  from 
the  dish  on  the  end  of  the  stirring-rod  and  allowing  it  to  run  into 
a  drop  of  a  dilute,  freshly-made  solution  of  ferricyanide  of  potas- 
sium placed  on  a  white  tile  or  capsule.  Dissolve  a  very  small 
crystal  of  ferricyanide  of  potassium  in  a  few  c.c.  of  water,  and 
place  a  number  of  drops  of  the  solution  on  a  white  tile  or  on  a 
flat-bottomed  capsule.  Run  the  carefully  standardized  solution 
of  bichromate  of  potassium  from  the  burette  into  the  deoxidized 
iron  solution  previously  placed  in  a  white  dish.  The  solution,  at 
first  colorless,  changes  gradually  to  a  decided  chrome-green  from 
the  reduction  of  "the  chromic  acid.  Test  the  progress  of  the  oxi- 
dation of  the  iron  solution  by  transferring  a  drop  of  it  on  the  end 
of  the  stirring-rod  to  one  of  the  drops  of  ferricyanide.  As  the 
blue  color  produced  becomes  less  intense,  add  the  bichromate 
more  slowly  and  make  the  test  more  frequently,  towards  the  end 
of  the  operation  after  the  addition  of  each  drop  of  bichromate. 
When,  finally,  no  color  appears  in  the  test-drops,  even  after  the  End  of  the 

reaction. 

lapse  of  several  moments,  the  oxidation  of  the  ferrous  salt  is 
complete,  and  the  amount  of  bichromate  used,  less  a  small  cor- 
rection for  the  zinc,  is  the  measure  of  the  amount  of  iron  in  the 
ore.  The  ferricyanide  of  potassium  employed  must,  of  course,  Purity  of 

ferricy- 

be  perfectly  free  from  ferrocyanide :    it  may  be  tested  by  adding      anide. 
a  drop  of  ferric  chloride  solution  to  one  of  the  drops  of  ferri- 
cyanide solution,  the  absence  of  any  resulting  blue  color  in  the 


2I5  ANALYSIS   OF  IRON  ORES. 

test-drops    being   proof    of   the   purity  of    the   ferricyanide.     As 
deteranhia-  towards  the  end  of  the  operation  the  frequent  tests  become  rather 
tedious,  some  analysts  prefer  to  make  the  determinations  in  dupli- 
cate, using  the  first  to  get  an  approximate  result. 
Treatment  When  the  ore  is  completely  decomposed  by  HC1,  a  separate 

or  ores  r  • 

completely  treatment  of  the  residue  is  unnecessary,  and  the  ore  may  be 
poseTby  weighed  at  once  into  the  flask  and  treated  with  10  c.c.  HC1 
and  a  little  KC1O3  when  organic  matter  is  present.  When  the 
ore  is  completely  decomposed,  and  any  Cl  from  the  KC1O3 
driven  off,  add  30  c.c.  of  water,  and  proceed  with  the  deoxida- 
tion. 

Instead  of  deoxidizing  the  solution  of  ferric  chloride  by  zinc,  it 


NH4Hso3.   may  be  deoxidized  by  a  solution  of  bisulphite  of  ammonium.     In 

fact,  the  deoxidation  by  zinc  is  not  practicable  in  ores  containing 

inthepres-   much  TiO2,  for  the  TiO2  is  reduced  by  metallic  zinc  to  Ti2O3,  im- 

ence  of 

Tio2.  parting  a  purple  or  blue  color  to  the  solution,  and  acting  like  a 
solution  of  ferrous  salt  on  the  standard  solution  of  permanganate. 
In  deoxidizing  a  solution  of  ferric  chloride  by  this  method  it 
should  be  placed  in  a  flask  of  120  c.c.  capacity,  and  two  or  three 
small  spirals  of  platinum  wire  added  to  facilitate  the  subsequent 
boiling.  Add  cautiously  to  the  solution  (which  should  not  exceed 

Details 

of  the        40  c.c.  in  volume)  enough  ammonia  to  produce  a  slight  permanent 

method. 

precipitate  of  ferric  hydrate,  which  remains  even  after  vigorous 
shaking.  Add  now  5  c.c.  of  a  strong  solution  of  NH4HSO3,* 
shake  vigorously,  and  warm  the  flask  gently.  As  the  color  of 
the  solution — at  first  a  deep  red — fades,  increase  the  heat,  and 
finally  heat  to  boiling.  When  the  solution  is  quite  colorless,  add 
to  it  the  solution  of  the  residue  and  100  c.c.  H2SO4  mixed  with 
20  c.c.  H2O.  Boil  the  solution  until  all  the  sulphurous  acid  is 
driven  off.  When  the  escaping  steam  no  longer  smells  of  SO2, 
place  the  flask  in  cold  water,  wash  down  the  funnel  and  the  neck 
of.  the  flask,  filling  the  latter  quite  full  of  water,  and  when  the 

*  See  page  44. 


DETERMINATION  OF  TOTAL   IRON. 

solution  is  quite  cold  transfer  it  to  a  dish  and  titrate  with  a 
standard  solution. 

A  third  method  of  deoxidizing  the  solution  of  ferric  chloride 

by  SnCl2. 

is  used,  in  which  the  reducing  agent  is  a  solution  of  stannous 
chloride.  The  investigations  of  Zimmerman*  and  Reinhardtf 
have  made  this  method  of  reduction  a  favorite  one,  especially 
when,  by  the  use  of  phosphoric  acid  and  manganous  sulphate, 
the  subsequent  titration  with  potassium  permanganate  is  practica- 
ble. The  details  are  as  follows :  Prepare  the  following  solutions : 

1.  Phosphoric    acid     solution:     Dissolve    200    grammes    of 
crystallized  manganous  sulphate  in    I   litre  of  water,  add  a  few 
drops  of  sulphuric  acid,  and  filter.     Add  to  this  I  litre  of  phos- 
phoric acid  (1.3  sp.  gr.),  600  c.c.  water,  and  400  c.c.  strong  sul- 
phuric acid. 

2.  Stannous    chloride    solution:     Dissolve    120   grammes   of 
granulated  tin,  free  from  iron,  in  500  c.c.  hydrochloric  acid  (1.19 
sp.  gr.),  dilute  to    I   litre,  and   filter  through  asbestos.     To  the 
filtrate  add  I  litre  of  hydrochloric  acid  (1.124  SP-  gr-)  and  2  litres 
of  water. 

3.  Mercuric    chloride    solution :     Dissolve    50    grammes    of 
mercuric  chloride  in  I  litre  of  water  and  filter. 

Dissolve  I  gramme  of  the  ore  in  30  c.c.  strong  hydrochloric 
acid  (if  necessary,  ignite,  and  fuse  the  residue  with  a  little  sodium 
carbonate,  dissolve  in  water  and  hydrochloric  acid,  and  add  to  the 
main  solution),  transfer  to  a  150  c.c.  Erlenmeyer  flask,  heat  to 
boiling,  and  add,  from  a  burette,  stannous  chloride  solution  until 
the  color  of  the  solution  fades  completely.  Pour  into  the  dish 
(page  214)  600  c.c.  of  water  and  add  to  it  60  c.c.  of  the  phos- 
phoric acid  solution.  To  the  deoxidized  solution  in  the  flask 
add  60  c.c.  of  the  mercuric  chloride  solution,  pouring  it  all  in  at 
once,  shake  vigorously  and  wash  the  solution  out  into  the  dish, 
using  plenty  of  wash  water,  and  titrate  with  permanganate  in 

*  Berichte  d.  Chem.  Ges.,  1884,  xv.  779. 
f  Chem.  Zeit.,  xiii.  324. 


2i 8  ANALYSIS   OF  IRON  ORES. 

the  usual  way.  The  phosphoric  acid  makes  the  solution  nearly 
colorless  by  forming  ferric  phosphate,  and  the  end  reaction  is  very 
sharp. 

The  mercuric  chloride  should  not  be  added  until  everything 
is  ready  for  the  titration,  as  the  absence  of  any  deoxidizing  sub- 
stance may  cause  the  solution  to  become  slightly  oxidized  on 
standing. 

Mixer  and  Dubois*  give  several  modifications  of  the  method 
as  used  in  the  Lake  Superior  region.  They  use  a  solution  of 
potassium  permanganate  of  such  strength  that  I  c.c.  equals  two 
per  cent,  of  iron  when  one-half  gramme  of  ore  is  used.  They 
use  for  standardizing  the  permanganate  an  iron  ore  the  amount  of 
iron  in  which  is  accurately  known,  and  if  the  permanganate  is  not 
exactly  of  the  proper  strength,  they  use  such  a  weight  of  the  ore, 
approximating  0.5  gramme,  that  the  reading  of  the  burette  multi- 
plied by  2  gives  the  percentage  of  iron.  Necessarily  this  implies 
the  use  of  the  same  weight  of  the  ore  to  be  analyzed.  They  also 
add  to  the  ore  about  2.5  c.c.  of  a  25  per  cent,  solution  of  stannous 
chloride  before  adding  the  hydrochloric  acid,  as  this  is  said  to 
very  much  hasten  the  solution  of  the  ore. 

Methods  for  Standardizing  the  Solutions. 
It  is  of  the  utmost  importance  that  the  value  of  the  standard 
affecting     solution  employed  should  be  determined  with  the  greatest  accu- 
racv  *f  t^le  results  obtained  by  its  use  are  to  be  anything  but  mere 
approximations.     To  do  this,  not  only  should  the  reagents  em- 
the  stand-    ployed  be  pure,  but  the  conditions  under  which  the  standard  is 

ard 

fixed  should  be,  as  nearly  as  practicable,  those  under  which  it  is 
employed  in  actual  use.  The  conditions  referred  to  are  not  only 
those  of  temperature,  dilution,  etc.,  but  of  the  actual  chemical 
composition  of  the  liquid  acted  on  by  the  standard  solution  by 
which  its  value  is  determined. 

The  best  reagent  to  employ  is  a  solution  of  ferric  chloride 

*  Journal  of  the  American  Chem.  Soc.,  vol.  xvii.  p.  405. 


DETERMINATION  OF   TOTAL   IRON. 


2I9 


of  known  strength.  To  prepare  this,  dissolve  100  grammes  of 
wrought  iron  (free  from  manganese  and  arsenic,  and  in  which  the 
phosphorus  has  been  accurately  determined)  in  nitric  acid,  evapo- 
rate to  dryness  in  a  capsule,  and  heat  until  the  nitrate  of  iron  is 
largely  decomposed  and  the  mass  separates  easily  from  the  bottom 
and  sides  of  the  capsule.  Transfer  to  a  piece  of  platinum-foil 
with  the  edges  turned  up,  and  heat  for  some  time  in  a  muffle 
at  a  very  high  temperature,  or  heat  it,  a  portion  at  a  time,  in  a 
crucible  at  the  highest  temperature  obtainable  by  a  blast-lamp. 
Grind  the  entire  mass  very  fine  in  an  agate  mortar,  dissolve  in 
HC1,  evaporate  to  dryness,  redissolve  in  dilute  HC1,  filter  to  get 
rid  of  SiO2,  and  dilute  the  solution  to  about  4  litres.  Twenty  c.c. 
of  this  solution  will  contain  about  .5  gramme  Fe,  and  it  may  be 
kept  indefinitely  in  a  glass-stoppered  bottle  sealed  with  paraffine, 
or  after  being  thoroughly  mixed  it  may  be  preserved  in  a  number 
of  smaller  bottles  properly  secured. 

Wash  out  and  dry  thoroughly  three  of  the  small  flasks  used 
for  deoxidizing  the  solutions  of  the  ores,  weigh  them  to  within 
I  mg.,  and  measure  into  each  a  portion  of  the  ferric  chloride 
solution  ranging  from  15  to  25  c.c.  in  volume.  Weigh  the  flasks 
and  their  contents  ;  the  differences  between  the  first  and  second 
weights  are  the  weights  of  the  ferric  chloride  solution  taken. 
Transfer  the  solution  carefully  from  each  flask  to  a  platinum  dish, 
dilute,  boil,  precipitate  by  NH4HO,  filter,  wash,  dry,  ignite,  and 
weigh  the  precipitate  with  the  precautions  mentioned  farther 
on.  The  precipitate  is  Fe2O3  -f  P2O5.  Subtract  from  this  weight 
the  amount  of  P2O5  in  this  weight  of  the  material,  and  the  remain- 
der will  be  the  weight  of  Fe2O3  in  the  amount  of  solution  used. 
Suppose,  for  example,  that  the  original  iron  contained  .1  per  cent. 
P,  this  would  be  equivalent  to  0.229  Per  cent.  P2O5,  but,  as  the  iron 
has  been  oxidized  to  Fe2O3,  the  percentage  of  P2O5  in  the  iron  as 
oxide  would  be  only  ^  as  great  as  in  the  iron  itself,  the  weight  as 
oxide  being  ^  as  great  as  it  was  as  Fe.  Therefore  multiply  .229 
per  cent,  by  .7  for  the  percentage  of  P2O5  in  the  Fe2O3,  which 


Preparation 

of  ferric 

chloride 


thes 


strength  ' 


solution. 


Example 

JrateThe 
method- 


220  ANALYSIS   OF  IRON  ORES. 

gives  .16  per  cent.  P2O5.  If  we  further  suppose  that  the  weight  of 
Fe2O3-hP2O5  obtained  was  .8131  gramme,  .16  per  cent,  of  this 
would  be  .0013  gramme,  the  weight  of  P2O5  in  the  precipitate, 
and  .8131  —  .0013  =  . 8118  gramme,  the  weight  of  Fe2O3  in  the 
amount  of  solution  taken.  Divide  this  weight  by  the  weight  of 
the  solution,  and  the  result  is  the  weight  of  Fe2O3  in  I  gramme 
of  the  solution  of  ferric  chloride.  Take  the  mean  of  the  three 
results  obtained  in  this  way,  and  call  this  result  the  value  of 
the  ferric  chloride  solution  in  Fe2O3,  or  multiply  by  .7  for  its 
value  in  Fe. 

To  standardize  the  permanganate  or  bichromate  solution, 
weigh  out  three  portions  of  the  ferric  chloride  solution  into  the 
flasks,  reduce  them  by  the  method  selected,  and  titrate  the  re- 
duced solutions  exactly  as  directed  above.  Before  calculating  the 
strength  of  the  standard  solution  a  small  correction  must  be  ap- 
plied to  the  burette  reading,  due  to  the  fact  that  a  definite  amount 
of  oxidizing  solution  is  required  to  produce  the  end  reaction  in 
all  cases  where  permanganate  is  used,  and,  when  bichromate 
is  used,  in  those  cases  where  zinc  has  been  the  deoxidizing 
agent. 
Determina-  Treat  3  grammes  of  zinc  in  a  small  flask  with  5  c.c.  HC1  and 

tion  of 

the  cor-  20  c.c.  H2O,  add  gradually  10  c.c.  H2SO4  and  20  c.c.  H2O.  When 
for  zinc,  the  zinc  has  all  dissolved,  place  the  flask  in  cold  water  until  the 
solution  is  cold.  Wash  it  out  into  the  dish,  dilute  to  I  litre,  add 
20  c.c.  ferric  chloride  solution  (free  from  ferrous  salt),  and  drop  in 
the  standard  solution  until  the  end  reaction  is  obtained.  Subtract 
the  correction  thus  obtained  from  every  burette  reading.  To 
calculate  the  strength  of  the  standard  solution,  therefore,  subtract 
the  correction  from  the  burette  reading,  and  the  result  is  the 
absolute  volume  of  the  standard  solution  required  to  oxidize  the 
ferrous  salt  in  the  solution  operated  on.  Knowing  then  the 
weight  of  the  ferric  chloride  solution  used,  the  amount  of  Fe  in 
each  gramme  of  the  solution,  and  the  volume  of  the  standard 
required  to  oxidize  this  amount,  the  value  of  each  c.c.  of  the 


DETERMINATION  OF  TOTAL   IRON.  221 

standard  solution  is  found   by  multiplying  the  weight  of  ferric  Calculation 
chloride  solution  used  by  the  value  of  each  gramme  in  Fe,  and     value 
dividing  the  amount  by  the  number  of  c.c.  of  the  standard  used     standard 
in  titrating.     The  mean  of  the  results  obtained  in  the  three  por- 
tions used  should  be  taken  as  the  value  of  the  standard  solution. 
An  example  will  illustrate  the  method  of  computation,  and,  as 
logarithms  very  much  facilitate  these  calculations,  they  will  be 
given  in  the  example  as  well. 

Weight  of  empty  flask 22.8817  Example  of 

Weight  of  flask  -f-  ferric  chloride  solution 40.0640 

Weight  of  ferric  chloride  solution  used 17.1823  =  ^.1.2350813 

Value   of  ferric  chloride  solution,  determined   as  on 

p.  219 i  gramme  =  .03227  gramme  Fe  =  log.  8.5087990 — 10 

Fe  in  ferric  chloride  solution  used 55448  gramme  =  log.  9.7438803 — IO 

Burette  reading  after  titration =82.0    c.c. 

Less  correction 0.25 

Corrected  reading 81.75  c.c.  =r  log.  1.9124878 


I  c.c.  standard  solution — .0067826  gramme  Fe  =log.  7.8313925 — 10 

Of  course  in  calculating  the  amount  of  Fe  in  an  ore  it  is  only  calculation 
necessary  to  get  the  logarithm  of  the  corrected  reading  (page  220)     Lore"1 
and  add  it  to  the  logarithm  of  the  standard  solution  as  found 
above,  the  number  corresponding  to  the  resulting  logarithm  being 
the  weight  of  Fe  in  grammes  in  the  ore.     This  multiplied  by  100 
will  give  the  percentage. 

Very  fine  iron  wire  may  be  used  to  standardize  the  solutions,  Use  of  iron 
instead  of  a  standard  solution  of  ferric  chloride.     Weigh  into  the     standard- 
reducing  flasks  from  .4  to  .6  gramme  of  fine  iron  wire  (page  55) 
which  has  been  carefully  rubbed  with  fine  sand-paper  and  wiped 
clean  with  a  linen  rag.     Dissolve  in  10  c.c.  HC1  and  20  c.c.  H2O, 
with  the  addition  of  a  few  small  crystals  of  KC1O3.     Deoxidize 
carefully,  and  titrate  as  before  directed.     Multiply  the  weight  of 
iron  wire  by  .998  to  get  the  absolute  amount  of  Fe  used,  apply 
the  proper    correction  to    the  burette   reading,  and  calculate  the 
value  of  the  standard. 


222 


ANALYSIS   OF  IRON  ORES. 


Use  of  fer- 
rous sul- 
phate or 
ammonio- 
ferrous 
sulphate. 


Degree  of 
concen- 
tration of 
standard 
solutions. 


Preparation 
and  pres- 
ervation of 
solutions. 


Ferrous  sulphate,  FeSO4,7H2O,*  containing  20.1439  Per  cent. 
Fe,  or  the  double  sulphate  of  iron  and  ammonium  FeSO4,(NH4)2 
SO4,6H2O,f  containing  14.2857  per  cent,  or  almost  exactly  \  of 
its  weight  of  Fe,  may  be  used  instead  of  ferric  chloride  solution  or 
iron  wire  to  determine  the  value  of  the  standard  solutions.  The 
pure  salts  are  generally  weighed  off,  dissolved  in  water  with  10  c.c. 
H2SO4,  added  and  titrated  direct,  but  they  are  not  so  satisfactory 
in  use  as  the  first  and  second  methods  described.  It  is  important 
to  have  the  standard  solutions  of  the  proper  strength ;  that  is, 
neither  too  dilute  nor  too  concentrated  for  convenience  in  work- 
ing. As  iron  ores  rarely  contain  more  than  60  per  cent,  metallic 
iron,  a  standard  solution  100  c.c.  of  which  are  equal  to  .66 
gramme  Fe  will  be  found  sufficiently  concentrated  to  avoid  the 
necessity  of  refilling  the  burette  for  a  determination ;  and  where 
ores  much  poorer  than  this  are  habitually  used  the  solutions  may 
be  correspondingly  more  dilute. 

When  permanganate  of  potassium  is  added  to  a  solution  of 
ferrous  sulphate  the  reaction  is  ioFeSO4  +  2KMnO4  -f  8H2SO4  = 
5Fe2(SO4)3  +  K2SO4  +  2MnSO4  -f  8H2O,  or  316.2  parts  by  weight 
of  KMnO4  will  oxidize  560  parts  by  weight  of  Fe,  or  3.727 
grammes  KMnO4  to  the  litre  will  give  a  solution  of  about  the 
strength  required. 

In  the  case  of  bichromate  of  potassium  the  reaction  is  6FeSO4 
+  K2Cr207  +  7H2S04  -  3Fe2(SO4)3  +  K2SO4  +  Cr2(SO4)3  -f  7H2O, 
or  294.5  parts  by  weight  of  K2Cr2O7  will  oxidize  336  parts  of  Fe, 
or  5-785  grammes  of  bichromate  of  potassium  dissolved  in  I 
litre  of  water  will  give  a  solution  100  c.c.  of  which  will  be 
equivalent  to  about  .66  gramme  Fe. 

To  prepare  the  solutions,  therefore,  dissolve  the  above  weights, 
or  multiples  of  them,  in  pure  distilled  water,  allow  the  solution 
to  stand  for  some  little  time,  filter  through  asbestos,  and  dilute  to 
the  proper  volume.  Mix  thoroughly  by  shaking  in  the  bottle, 


*  See  page  55. 


f  See  page   56. 


DETERMINATION  OF  FERROUS    OXIDE. 


and  standardize  as  above  directed.  The  solutions  should  be  kept 
in  glass-stoppered  bottles  in  a  dark  closet,  and  the  bottles  should 
be  well  shaken  whenever  the  solution  is  used. 


DETERMINATION    OF   IRON    EXISTING   AS   FeO. 

Many  iron  ores  contain  iron  in  the  state  of  FeO,  and  this 
FeO  may  be  either  soluble  or  insoluble  in  HC1.  To  determine  FeO  soluble 
the  FeO  soluble  in  HC1,  weigh  I  gramme  of  the  finely-ground 
ore  into  the  flask  A,  Fig.  91,  of  about  100  c.c.  capacity.  Close 
the  flask  with  a  rubber  stopper  fitted  with  the  two  glass  tubes  B 
and  C,  and  place  it  in  the  position  shown  in  the  sketch.  Connect 
the  tube  C  by  means  of  a  piece  of  rubber  tubing  with  the  bent 
tube  D  dipping  below  the  surface  of  the  water  in  the  beaker  E. 
Pass  a  current  of  CO2  through  the  tube  B  until  all  the  air  is 
expelled,  then  remove  for  a  moment  the  rubber  tube  connecting 
B  with  the  source  of  CO2,  and  by  means  of  a  small  funnel  and 
rubber  connector  introduce  into  the  flask  A,  through  B,  10-12 
c.c.  strong  HC1,  and  establish  the  current  of  CO2  as  before.  Heat 
the  flask  carefully,  and  when  the  ore  is  entirely  decomposed,  or 
the  HC1  ceases  to  exert  any  further  action  on  it,  remove  the  source 
of  heat,  stop  the  current  of  CO2  for  a  moment,  cool  the  flask  with 
the  hand,  and  allow  the  partial  vacuum  thus  formed  to  draw  the 
water  from  E  back  into  A.  Turn  on  the  current  of  CO2  again, 
place  a  dish  of  cold  water  under  the  flask  A,  and  allow  the  solu- 
tion to  cool.  Dissolve  in  a  small  flask  3  grammes  of  metallic 
zinc  in  10  or  15  c.c.  H2SO4,  diluted  with  the  proper  quantity  of 
water,  cool  it,  and  have  it  ready  to  pour  into  the  titrating-dish 
by  the  time  the  solution  in  the  flask  A  is  cool.  Wash  out  the 
solution  of  the  ore  from  the  flask  A  into  the  dish,  add  the  zinc 
solution,  dilute  to  I  litre,  and  titrate  with  a  standard  solution. 
Subtract  from  the  burette  reading  the  proper  correction,  calculate 
the  percentage  of  Fe,  divide  by  7,  and  multiply  by  9.  The  result  is 


224 


ANALYSIS   OF  IRON  ORES. 


tion  of 


the  percentage  of  FeO  in  the  ore  soluble  in  HC1.  Allow  the  solu- 
tion  in  the  dish  to  stand  for  a  few  minutes,  when  all  the  undecom- 
posed  particles  of  ore  will  settle.  Draw  off  the  greater  part  of 


in  HC1. 


FIG.  91. 


Q 


the  clear  supernatant  fluid  with  a  siphon,  wash  the  sediment  into 
a  beaker  with  a  jet  of  cold  water,  filter  on  a  thin  felt*  in  a  Gooch 
crucible,  and  wash  the  sediment  on  the  felt  with  cold  water. 
Transfer  the  felt  and  sediment  to  a  platinum  crucible,  pour  into 
the  crucible  5-10  c.c.  HC1  and  about  half  the  quantity  of  HF1, 

*  The  asbestos  of  which  the  felt  is  made  must  be  free  from  FeO. 


>».= 


DETERMINATION  OF  FERROUS   OXIDE. 

cover  the  crucible,  and  place  it  in  the  water-bath  shown  in  Fig. 
92.  The  crucible  rests  on  a  platinum  triangle  fixed  over  the  hole 
in  the  centre  of  the  tip  of  the  bath.  Around  this  hole  is  a  groove 

FIG.  92. 


225 


j.. o 


NCHES 


in  which  a  funnel  stands  as  shown  in  the  cut,  while  the  water  in 
the  groove  forms  a  tight  joint.*  Pass  a  current  of  CO2  or  coal- 
gas  through  the  tube  in  the  side  of  the  bath,  as  figured  in  the  cut, 
to  exclude  the  air,  and  heat  the  bath  until  the  residue  and  felt  are 
completely  dissolved.  Wash  the  crucible  out  into  the  titrating- 

*  Avery,  Chem.  News,  xix.  270;  Wilbur  and  Whittlesay,  Crook's  Select  Methods, 
Page  133- 


226  ANALYSIS   OF  IRON  ORES. 

dish,  into  which  have  been  poured  just  previously  3  grammes  of 
zinc  dissolved  in  H2SO4  and  enough  cold  water  to  make  the  solu- 
tion up  to  nearly  I  litre.  Titrate,  and  calculate  the  amount  of 
FeO  as  before. 

Separate  Of  course  separate  portions  of  the  ore  may  be  used  to  deter- 

mine  the  FeO  soluble  and  insoluble  in  HC1,  but  it  is  more  trouble- 
some,  and  experience  has  shown  that  it  is  no  more  accurate,  and 
soluble  in     -n  some  cases  less  accurate,  than  the  method  just  described. 

Total  FeO  The  total  FeO  may  also  be  determined  in  one  operation  by 

operation,  treating  I  gramme  of  the  ore  direct  in  the  crucible  with  20  c.c. 
HC1  and  20  c.c.  HF1,  but  it  is  often  difficult  to  get  the  ore  perfectly 
dissolved  even  by  prolonged  heating  in  the  bath,  and  the  ore  must 
be  ground  very  fine  in  the  agate  mortar.  It  is  necessary  to  re-- 
move the  funnel  from  time  to  time,  raise  the  lid  of  the  crucible, 
and  stir  the  contents  with  a  platinum  wire. 

When  the  ore  is  completely  decomposed  by  HC1,  or  when 
the  portion  undecomposed  contains  no  FeO,  the  treatment  of  the 
residue  is  unnecessary. 

When  an  ore  contains  much  organic  matter,  an  accurate  deter- 
mination of  FeO  is  often  impossible,  as  the  solution  of  the  ore  in 
HC1  reduces  some  of  the  ferric  salt. 


DETERMINATION    OF   SULPHUR. 

Sulphur  exists  in  two  conditions  in  iron  ores,  as  sulphur  in  the 
form  of  sulphides  and  as  sulphuric  acid  in  the  form  of  sulphates. 
Total  sui-      To  determine  the  total  sulphur,  weigh   I   gramme  of  the  finely- 
ground  ore  into  a  large  platinum  crucible,  add  to  it  10  grammes 
of   Na2CO3   and    a   little    KNO3   (less   than    I    gramme).*      Mix 

*  See  pages  46  and  48.  It  is  well  to  make  a  blank  determination,  using  the 
same  amounts  of  Na2CO3,  KNO3,  and  HC1,  applying  the  amount  of  BaSO4  found 
as  a  correction. 


DE1ERMINATION  OF  SULPHUR. 


22/ 


thoroughly  with  a  platinum  wire,  and  heat  carefully  over  a  large 
Bunsen  burner  or  blast-lamp  until  the  mass  appears  perfectly 
liquid  and  in  a  tranquil  state  of  fusion.  Run  the  fusion  well  up 
on  the  sides  of  the  crucible,  allow  it  to  cool,  and  treat  it  in  the 
crucible  with  boiling  water.  Pour  the  liquid  into  a  tall,  narrow 
beaker,  treat  the  crucible  again  with  boiling  water,  and  repeat  the 
operation  until  all  the  sodium  salts  are  dissolved  and  nothing 
remains  in  the  crucible  except  the  unavoidable  stains.  Stir  the 
liquid  in  the  beaker  well,  and  allow  the  oxide  of  iron  to  settle.  If 
the  solution  is  colored  red  or  green,  it  is  proof  of  the  presence  Evidence  or 
of  manganese  in  the  ore  ;  add  a  few  drops  of  alcohol,  which  will  ™e*"gand 
precipitate  the  manganese  as  oxide,  leaving  the  solution  colorless 
unless  the  ore  contains  chromium,  in  which  case  the  solution  will 
be  yellowish.  Decant  the  supernatant  liquid  on  a  small  filter, 
allowing  the  filtrate  to  run  into  a  No.  4  beaker,  fill  the  small  beaker 
nearly  full  of  hot  water,  stir  well,  and  allow  to  settle.  Decant  again 
on  the  filter,  and  repeat  the  operation  once  more.  Acidulate  the 
collected  filtrates  with  HC1  (about  20  c.c.  will  be  required),  evapo- 
rate to  dryness  in  the  air-bath,  redissolve  in  water  with  a  few  drops 
of  HC1,  filter  into  a  No.  3  beaker,  heat  the  filtrate  to  boiling,  and 
add  10  c.c.  of  a  solution  of  chloride  of  barium.*  Allow  to  stand 
for  some  hours,  filter  on  the  Gooch  crucible  or  on  a  small  ashless 
filter,  ignite,  and  weigh  as  BaSO4,  which  multiplied  by  .1376  gives 
the  weight  of  S.  The  insoluble  portion  from  the  aqueous  solu- 
tion of  the  fusion  may  be  used  to  determine  the  total  iron  in  the 
ore,  and  is  very  convenient  for  this  purpose  in  ores  difficult  to 
dissolve.  Pour  into  the  crucible  in  which  the  fusion  was  made 
about  10  c.c.  HC1,  place  the  lid  on  the  crucible,  and  warm  the 
crucible  slightly  to  dissolve  the  adhering  oxides,  dilute  with 
about  an  equal  bulk  of  water,  and  pour  it  on  the  small  filter 
through  which  the  aqueous  solution  was  decanted,  allowing  it  to 
run  into  the  beaker  which  contains  the  residue  of  oxide  of  iron, 


iron  in  the 


fusion' 


*  See  page  51. 


228  ANALYSIS   OF  IRON  ORES. 

etc.  Wash  out  the  crucible,  pouring  the  washings  on  the  filter, 
and  wash  the  filter  free  from  iron  with  a  jet  of  cold  water.  Evap- 
orate the  solution  in  the  beaker  to  dryness,  redissolve  in  10  c.c. 
HC1,  and  transfer  the  solution  of  ferric  chloride,  the  silica,  etc., 
to  one  of  the  small  flasks,  deoxidize,  and  titrate  as  directed. 

The  sulphur  which  exists  as  sulphuric  acid  in  an  iron  ore 
is  usually  combined  with  either  calcium  or  barium :  as  sulphate 
of  calcium  or  of  any  of  the  other  alkaline  earths  except  barium, 
of  the  alkalies,  or  of  the  metals,  it  is  soluble  in  HC1 ;  as  sulphate 
of  barium  it  is  practically  insoluble.  We  may,  therefore,  deter- 

Determi-       mine  the  soluble  sulphates   as  follows  :  Boil   10  grammes   of  the 
soiubie°      ore  with  30  c.c.  HC1  and  60  c.c.  water,  filter  from  the  mass  of  the 
sulphates.    uncjjssoivecj    ore>  evaporate  the    filtrate  to  dryness,  redissolve    in 
HC1  and  water  (1—2),  filter  into  a  No.  2  beaker,  nearly  neutral- 
ize by  NH4HO,  heat  to  boiling,  and    precipitate  by  BaCl2  solu- 
tion.     Filter    and    wash    the    precipitate,    ignite,    and    weigh    as 
BaSO4,  which  contains  34.352  per  cent.  SO3. 

Determi-  To  determine  the  sulphuric  acid  which  exists  as  sulphate  of 

sulphate  barium,  treat  10  grammes  of  the  ore  with  50  c.c.  HC1  until  the 
um'  ore  appears  to  be  decomposed.  Evaporate  to  dryness,  redis- 
solve in  dilute  HC1  (1-3),  dilute,  filter,  and  wash  the  insoluble 
matter  thoroughly.  Ignite  and  fuse  the  insoluble  matter  with 
Na2CO3,  treat  the  fused  mass  with  hot  water,  and  filter.  In 
the  filtrate  is  the  sulphuric  acid  as  sulphate  of  sodium,  while 
the  barium  remains  on  the  filter  as  carbonate  of  barium.  It  is 
safer  to  calculate  the  sulphate  of  barium  from  the  amount  of 
barium  rather  than  from  the  amount  of  sulphuric  acid,  as  the 
ore  may  contain  sulphides  (pyrites,  etc.),  which  are  not  decom- 
posed by  HC1,  but  are  decomposed  and  partly  oxidized  by  fusion 
with  Na2CO3.  The  other  forms  of  barium  besides  the  sulphate 
(silicate  and  carbonate)  are  readily  decomposed  by  HC1,  and 
are  not  likely  to  be  found  with  the  barium  in  the  insoluble 
residue.  It  is,  of  course,  possible  to  suppose  the  coexistence 
of  silicate  or  carbonate  of  barium  and  of  sulphate  of  calcium 


. 

DETERMINATION  OF  PHOSPHORIC  ACID. 

in  an  ore,  and  the  consequent  formation  of  sulphate  of  barium 
when  the  ore  is  decomposed  by  HC1;  but,  as  the  soluble  sul- 
phuric acid  is  determined  in  one  operation  and  the  insoluble 
in  another,*  the  total  amount  of  sulphuric  acid  existing  as  such 
is  determined,  and  the  object  of  the  analysis  attained.  To  deter- 
mine the  barium,  then,  treat  the  insoluble  matter  obtained  by 
the  filtration  of  the  aqueous  solution  of  the  fusion  by  dilute 
HC1,  evaporate  to  dryness  to  render  SiO2  insoluble,  redissolve 
in  water  with  a  few  drops  of  HC1,  filter  into  a  No.  2  beaker, 
heat  the  filtrate  to  boiling,  and  add  a  few  drops  of  H2SO4 
diluted  with  a  little  water.  Allow  the  precipitate  to  settle,  filter, 
wash,  ignite,  and  weigh  as  BaSO4,  from  which  weight  calculate 
the  amount  of  SO3  in  the  ore  insoluble  in  HC1.  To  find  the 
amount  of  sulphur  existing  as  sulphides,  subtract  from  the  total 
S  the  amount  of  S  in  the  SO3  found  as  sulphates. 


DETERMINATION    OF   PHOSPHORIC   ACID. 

Treat  5  or  IQ  grammes  of  the  finely-ground  ore  in  30  or  solution  of 
60  c.c.  HC1.  (With  low  phosphorus  ores  use  10  grammes ;  with 
others,  5  grammes.)  When  the  ore  is  decomposed,  evaporate 
to  dryness,  redissolve  in  20  or  40  c.c.  HC1,  dilute,  filter,  and 
proceed  exactly  as  directed  in  the  determination  of  phosphorus 
in  iron  and  steel,  page  81  et  seq.  The  weight  of  the  Mg2P2O7 
multiplied  by  .63788  gives  the  weight  of  the  P2O5.  The  weight 
of  the  phospho-molybdate  of  ammonium  multiplied  by  .03735 
gives  the  weight  of  the  P2O5. 

Titanic   acid    is  very    generally    found    associated    with    iron  Precautions 
ores,  and  may  be   regarded   as    one  of  the   usual   constituents. 

*  The  insoluble  matter  from  the  treatment  of  10  grammes  of  the  ore  with  HC1 
for  the  determination  of  soluble  sulphates,  page  228,  may  be  used  to  determine  the 
sulphate  of  barium. 


230 


ANALYSIS   OF  IRON  ORES. 


Means  of 
recogniz- 
ing titan- 
iferous 
ores. 


Ores  con- 
taining 
barium. 


Additional 
test  for 
titanic 
acid. 


As  mentioned  on  page  86  its  presence,  if  overlooked,  may  lead 
to  serious  errors  in  the  determination  of  phosphoric  acid.  When 
an  ore  contains  much  titanic  acid  it  may  readily  be  recognized 
by  the  peculiar  milky  appearance  of  the  solution  when  it  is 
diluted  preparatory  to  filtering  off  the  insoluble  matter,  and  by 
the  strong  tendency  it  shows  to  run  through  the  filter  as  soon 
as  the  attempt  is  made  to  wash  the  insoluble  matter  with  water. 
Smaller  quantities  of  titanic  acid  may  be  recognized  by  the 
clouding  of  the  solution  when  it  is  deoxidized  by  bisulphite  of 
ammonium,  as  noted  on  page  89.  In  the  latter  case,  however, 
this  clouding  may  be  caused  by  the  formation  of  sulphate  of 
barium  when  the  ore  contains  the  latter  element  in  the  form 
of  carbonate  or  silicate.  Silica  in  the  solution  may  also  cause 
a  cloud  under  those  circumstances  which  closely  resembles  that 
caused  by  titanic  acid,  while  sulphate  of  barium  may  readily 
be  distinguished  from  either  by  its  granular  appearance  and  its 
tendency  to  settle  to  the  bottom  of  the  beaker. 

The  insoluble  residue  from  the  solution  of  the  ore  in  HC1 
should,  therefore,  be  treated  to  recover  any  P2O5  which  may 
have  remained  insoluble  in  combination  with  TiO2<*  An  ad- 
ditional test  for  the  presence  of  titanic  acid,  and  one  that  rarely 
fails  even  with  very  small  amounts,  is  to  dissolve  the  insoluble 
matter  from  the  aqueous  solution  of  the  fusion  of  the  residue 
from  the  HF1  and  H2SO4  treatment  of  the  insoluble  residue 
from  the  ore,  in  dilute  HC1,  allowing  it  to  run  into  a  test-tube 
and  adding  metallic  zinc.  When  titanic  acid  is  present  the  solu- 
tion becomes  first  colorless,  and  then  pink  or  purple,  and  finally 
blue  from  the  formation  of  Ti2O3.  The  simplest  way  is  to  pro- 


*  When  HF1  is  not  available,  fuse  the  residue  with  Na2CO3,  treat  the  fused 
mass  with  hot  water,  filter,  acidulate  the  filtrate  with  HC1,  evaporate  to  clryness  to 
render  SiO2  insoluble.  Redissolve  in  water  with  a  little  HC1,  filter,  and  add  the 
filtrate  to  the  main  solution,  or  add  a  little  Fe2Cl6,  and  make  a  separate  acetate 
precipitation  in  this  portion,  adding  the  solution  to  the  solution  of  the  main  acetate 
precipitation. 


DETERMINATION  OF   TITANIC  ACID.  231 

ceed  as  directed  an  pages  88  and  89  when  using  the  acetate 
method,  or  on  page  94  when  using  the  molybdate  method. 
These  methods  are  not  practicable,  however,  when  the  ore 
contains  a  very  large  amount  of  TiO2,  and  recourse  must  be 
had  to  the  method  described  on  page  86  et  seq.,  involving  the 
fusion  of  the  acetate  precipitate  and  the  residue  from  the  treat-  Fusion  of 
ment  of  the  insoluble  matter  with  HF1  and  H2SO4,  with 


and  a  little  NaNO3.  It  is  best  to  pursue  this  method  at  any 
rate  whenever  TiO2  is  also  to  be  determined,  as  the  same  por- 
tion can  be  used  for  the  estimation  of  both  TiO2  and  P2O5,  and 
the  aggregate  labor  involved  is  much  lessened. 


DETERMINATION    OF   TITANIC   ACID. 

The  determination  of  titanic  acid  has  always  presented  many  Difficulties 
difficulties,  and  its  separation  from  a  large  amount  of  oxide  of  CiPitation 
iron  and  alumina  has  been  far  from  satisfactory,  besides  being 
most  tedious.  The  principal  sources  of  error  in  the  estimation 
of  titanic  acid  in  iron  ores  are  the  tendency  of  P2O5  to  prevent  the 
precipitation  of  TiO2  by  boiling,  when  its  sulphuric  acid  solution 
contains  P2O5  and  ferrous  sulphate,  and  the  liability  of  A12O3  to 
separate  out  with  the  TiO2  when  the  latter  is  precipitated  under 
the  circumstances  above  mentioned.  There  is  also  a  mechanical 
difficulty,  caused  by  the  adhesion  of  the  precipitated  TiO2  to  the 
bottom  and  sides  of  the  beaker,  from  which  it  can  sometimes  be 
removed  only  by  boiling  with  a  strong  solution  of  caustic  potassa. 
The  admirable  series  of  experiments  carried  out  by  Dr.  Gooch  * 
on  the  separation  of  aluminium  and  titanium  suggests  a  method 
which  renders  the  determination  of  TiO2  in  iron  ores  much  less 
troublesome,  while  adding  greatly  to  the  accuracy  of  the  results. 

*  Proceedings  Am.  Acad.  Arts  and  Sciences,  New  Series,  vol.  xii.  p.  435. 


232 


ANAL  YSIS   OF  IRON  ORES. 


Details 
of  the 

method. 


Principles 
involved. 


In  carrying  out  the  details  of  the  method,  dissolve  5  or  10 
grammes  of  the  ore  in  HC1,  and  proceed  exactly  as  in  the  deter- 
mination of  P2O5,  by  fusing  the  residue  from  the  treatment  of 
the  insoluble  matter  by  HF1  and  H2SO4  and  the  acetate  pre- 
cipitate with  Na2CO3  and  a  little  NaNO3,*  and  then  complete 
the  operation  exactly  as  described  in  the  determination  of  Ti  in 
pig-iron.f 

The  essential  points  in  this  method  are — i.  Separation  of  the 
TiO2  from  the  mass  of  Fe2O3  by  acetate  of  ammonium  in  the 
deoxidized  solution.  2.  Separation  from  all  the  P2O5  and  the 
greater  part  of  the  A12O3  by  fusion  with  Na2CO3,  by  which  means 
a  titanate  -of  sodium  insoluble  in  water  is  formed,  and  at  the  same 
time  phosphate  and  aluminate  of  sodium  soluble  in  that  men- 
struum. 3.  Separation  from  the  last  traces  of  A12O3  from  the  iron, 
calcium,  etc.,  by  precipitating  the  TiO2  in  the  thoroughly  deoxi- 
dized solution  in  the  presence  of  a  large  excess  of  acetic  acid  and 
some  SO2,  the  sulphuric  acid  being  all  in  the  form  of  sulphate 
of  sodium.  The  addition  of  a  large  excess  of  acetate  of  sodium, 
by  which  this  latter  condition  is  effected,  converts  all  the  sulphates 
of  iron,  calcium,  etc.,  into  acetates,  and  precipitates  the  TiO2 
almost  instantaneously  as  a  hydrate,  which  is  flocculent,  settles 
quickly,  shows  no  tendency  to  run  through  the  filter,  and  is 
washed  with  the  greatest  ease.  It  sometimes  happens  that  a  little 
FeO  is  precipitated  with  the  TiO2,  and  the  latter,  after  ignition, 
appears  discolored;  in  this  case  fuse  with  a  little  Na2CO3,  add 
H2SO4  to  the  cold  fused  mass,  dissolve,  and  repeat  the  precipita- 
tion with  acetate  of  sodium  in  the  presence  of  sulphurous  and 
acetic  acids  exactly  as  in  the  first  instance. 

A  number  of  experiments  covering  all  the  points  involved  in 
this  method  show  it  to  be  extremely  accurate  and  entirely  trust- 
worthy. 


*  See  page  86  et  seq. 


f  See  page  178  et  seq. 


DETERMINATION   OF  MANGANESE.  333 

DETERMINATION  OF  MANGANESE. 

When  manganese  alone  is  to  be  determined  in  an  ore,  any 
one  of  the  methods  described  under  the  determination  of  manga- 
nese in  iron  and  steel,  page  109  et  seq.,  may  be  used.  The  most 
convenient,  however,  is  Ford's  method  with  the  modifications  Ford>s 

-  f  method. 

necessary  in  the  analysis  of  pig-iron,  page  117.  The  only  change 
requisite  is  to  evaporate  the  solution  in  HC1  to  dryness  to  render 
silica  insoluble  before  filtering  off  the  insoluble  matter. 

In  the  determination  of  manganese  in  high  grade  manganese 
ores,  it  is  best  to  use  a  one-tenth  factor  weight  (0.3874  gramme) 
of  the  sample,  dissolve  in  hydrochloric  acid,  evaporate  to  dryness, 
redissolve  in  dilute  hydrochloric  acid  and  filter  off  the  insoluble 
matter.  Ignite  the  insoluble  matter  in  a  platinum  crucible,  fuse 
with  a  little  sodium  carbonate,  dissolve  in  water,  acidulate  with 
hydrochloric  acid,  and  evaporate  to  dryness.  Redissolve  in  dilute 
hydrochloric  acid  and  filter  into  the  main  solution.  Or,  treat  the 
ignited  insoluble  matter  with  sulphuric  and  hydrofluoric  acids, 
drive  off  the  hydrofluoric  and  the  excess  of  sulphuric,  cool,  add 
water  and  a  little  hydrochloric  acid,  and  heat  until  the  residue 
dissolves,  then  add  the  solution  to  the  main  solution  of  the  ore. 

Evaporate  the  main  solution  until  it  is  syrupy,  add  an  excess 
of  strong  nitric  acid  and  evaporate  off  the  hydrochloric  acid. 
Precipitate  by  potassium  chlorate  in  the  usual  way  and  filter 
through  asbestos.  Wash  the  precipitate  thoroughly  with  cold 
water  to  get  rid  of  the  calcium  nitrate,  which,  being  practically 
insoluble  in  strong  nitric  acid,  will  remain  with  the  precipitated 
manganese  dioxide,  unless  this  precaution  be  observed.  There  is 
no  danger  of  dissolving  the  manganese  dioxide  by  this  treatment. 

Proceed  with  the  determination  as  directed  on  page  116. 
Each  milligramme  of  manganese  pyrophosphate  is  a  tenth  of  one 
per  cent,  of  manganese  in  the  ore. 

In  using  the  acetate  method  it  is,  of  course,  necessary  that  The  acetate 
all  the  iron  should  be  in  the  form  of  Fe2Cl6,  and  also  that  there     method' 
should  be  no  oxidizing  agent  in  the  solution.     Even  a  very  small 


234 


ANALYSIS   OF  IRON  ORES. 

amount  of  FeCl2  will  cause  the  formation  of  a  "  brick-dust"  precipi- 
tate, which  cannot  be  kept  from  passing  the  filter  while  some  of 
the  iron  remains  dissolved  in  the  acetate  solution.  When,  there- 
fore, the  ore  contains  FeO,  it  should  be  oxidized  by  HNO3  or 
KC1O3,  and  the  excess  of  the  oxidizing  agent  removed  by  evapo- 
ration with  HC1. 

Volhard's  Method  Applied  to  High  Grade  Manganese  Ores. 

Volhard's  is  the  most  satisfactory  volumetric  method  for  high 
grade  manganese  ores.  Dissolve  I  gramme  of  the  ore  in  a  small 
beaker  in  hydrochloric  acid,  heat  until  the  chlorine  is  all  driven 
off,  wash  out  into  a  platinum  dish  (Fig.  36),  and  add  5  c.c.  strong 
sulphuric  acid  and  a  little  hydrofluoric  acid.  Evaporate  to  dry- 
ness  and  heat  until  the  sulphuric  acid  begins  to  volatilize.  Cool, 
dissolve  in  water,  transfer  to  a  300  c.c.  flask,  and  proceed  as 
directed  on  page  116,  except  that  100  c.c.  of  the  filtered  solution 
representing  one-third  of  a  gramme  of  the  ore  is  used. 

In  running  in  the  permanganate  it  is  necessary  to  heat  the 
solution  in  the  flask  after  there  appears  to  be  a  slight  excess. 
This  will  make  the  precipitate  settle  rapidly  and  generally  show 
the  necessity  for  adding  more  permanganate. 

A  large  number  of  comparative  analyses  have  shown  that  it 
is  necessary  to  add  one  one-hundredth  of  the  amount  obtained  to 
get  the  true  percentage  of  manganese ;  in  other  words,  the  results 
obtained  are  always  one  one-hundredth  too  low. 

For  instance,  if  by  calculation  the  ore  contains  50  per  cent, 
of  manganese  by  this  method,  the  true  result  is  50.5  per  cent. 

Pattinson's  Method.1 

Dissolve  in  hydrochloric  acid  such  a  quantity  of  the  sample 
as  shall  contain  not  more  than  0.25  gramme  of  manganese.  In 
high  manganese  ores  add  enough  ferric  chloride  to  the  solution 
to  make  the  iron  and  manganese  contents  about  equal.  Add 

1  Society  of  Chemical  Industry,  vol.  x.  No.  4. 


DETERMINATION  OF  MANGANESE. 


235 


calcium  carbonate  to  the  solution  until  it  is  slightly  red  in  color 
and  acidulate  by  adding  hydrochloric  acid  until  the  red  color 
disappears.  Add  sufficient  zinc  chloride  in  solution  to  give  0.5 
gramme  metallic  zinc.  Heat  to  boiling  and  dilute  with  boiling 
water  to  300  c.c.,  and  add  60  c.c.  of  a  solution  of  calcium  hypo- 
chlorite  containing  33  grammes  to  the  litre.  To  the  solution  of 
hypochlorite  just  before  using  it,  add  enough  hydrochloric  acid  to 
give  it  a  faint  greenish  tinge  after  agitation. 

Finally  add  3  grammes  of  calcium  carbonate  diffused  in  1 5  c.c. 
of  boiling  water,  and  after  stirring  well  2  c.c.  of  methyl  alcohol. 

Filter  on  a  large  filter  and  wash  with  water  at  65°  until  a  strip 
of  iodized  starch  paper  gives  no  indication  of  chlorine. 

Measure  into  a  beaker  100  c.c.  of  a  carefully  standardized 
strongly  acid  solution  of  ferrous  sulphate  containing  10  grammes 
of  iron  to  the  litre  and  place  the  precipitate  and  filter  in  it.  When 
the  precipitate  has  dissolved  add  cold  water  and  determine  the 
excess  of  ferrous  sulphate  by  a  standard  solution  of  potassium 
bichromate. 

When  the  ore  contains  much  organic  matter  it  should  be  fil-  FCO  and 
tered  off  before  attempting  to  oxidize  the  ferrous  salt,  as  it  is  quite     mftterta 
impossible  in  some  cases  to  destroy  the  organic  matter,  and  reso- 
lution of  the  evaporated  mass  in  HC1  causes  a  reduction  of  some 
of  the  ferric  salt. 

Many  manganiferous  iron  ores  contain  manganese  in  a  higher  Ores  con- 
state of  oxidation  than  the  protoxide,  and  the  determination  of  the 
excess  of  oxygen  is  often  necessary.  All  ores  of  this  character 
when  treated  with  HC1  evolve  chlorine  gas,  which, is  easily  recog- 
nized by  its  yellowish-green  color  and  peculiarly  irritating  odor. 
The  reaction  by  which  chlorine  is  liberated  is  MnO2  +  4HCl  = 
MnCl2  -f-  2H2O  -j-  2C1,  or  each  molecule  of  MnO2  =  87  corresponds 
to  2  molecules  of  Cl  =  70.90.  This  reaction  is  the  basis  of  Bun- 
sen's  method  for  the  estimation  of  the  amount  of  the  MnO2  in 
manganese  ores,  which  consists  in  driving  the  liberated  Cl  into  a 
solution  of  iodide  of  potassium,  and  determining  the  amount  of 


236 


Bunsen's 
method. 


ANALYSIS   OF  IRON  ORES. 

iodine  set  free,  by  starch  and  hyposulphite  solution.  When  the 
method  given  on  page  68  et  seq.  for  determining  sulphur  in  steel 
is  in  use,  the  solutions  employed  in  carrying  out  that  method 
(with  the  exception  of  the  iodine  in  iodide  of  potassium)  can  be 
used  in  this,  or  they  may  be  prepared  by  the  directions  there 
given,  for  use  in  this  method. 

Weigh  from  .5  gramme  to  I  gramme  of  the  finely-ground  ore 
into  the  flask  a,  Fig.  93,  pour  in  10  c.c.  strong  HC1,  connect  the 

FIG.  93. 


bent  tube  b  quickly  by  means  of  a  piece  of  gum  tubing,  and  heat 
the  flask  gently  at  first  and  finally  to  boiling  to  drive  all  the  Cl 
over  into  the  tube  r,  which  contains  a  strong  solution  of  pure 
iodide  of  potassium  free  from  iodate.  This  tube  is  placed  in  ice- 
water.  When  all  the  Cl  has  been  expelled  from  the  flask  a  and 
absorbed  in  c,  detach  the  latter,  wash  its  contents  into  a  large  dish, 


DETERMINATION  OF  MANGANESE. 


237 


add  a  little  starch  solution,  and  run  in  the  hyposulphite  until  the 
blue  color  just  vanishes.  If,  as  in  the  example  given  on  page  70,  Example. 
I  c.c.  of  the  hyposulphite  solution  is  equal  to  .01267  gramme  of 
iodine,  and  I  equivalent  of  chlorine  =3  5.  45  replaces  i  equiva- 
lent of  iodine  =  126.85  in  the  iodide  of  potassium,  i  c.c.  of  the 
hyposulphite  solution  would  be  equal  to  (126.85  :  35.45  ::  .01267: 
.003541)  .003541  gramme  of  chlorine;  and,  as  I  equivalent  of 
MnO2  =  87  is  equal  to  2  equivalents  of  chlorine  =  70.90,  i  c.c.  of 
the  hyposulphite  would  be  equal  to  (70.90  :  87  :  :  .003541  :  .004345) 
.004345  grammes  MnO2. 

In  most  laboratories,  however,  it  is  generally  more  convenient 
to  determine  the  amount  of  MnO2  in  an  ore  by  determining  its  oxi- 
dizing power  on  a  solution  of  ferrous  salt.  The  reaction  is  2FeSO4 
+  MnO2  +  2H2SO4  =  Fe2(SO4)3  +  MnSO4  +  2H2O,  or  2  equivalents 
of  Fe  =  1  12  are  equal  to  i  equivalent  of  MnO2  =  87.  Grind  in  an 


tion  by 

agate  or  Wedgwood  mortar  about  10  or  15  grammes  of  ferrous  means  of 
sulphate  or  ammonio-ferrous  sulphate,  and  weigh  out  two  portions,  Su7phate. 
one  of  2  grammes  and  one  of  3  to  8  grammes,  according  to  the 
quality  of  the  manganese  ore.  One  gramme  of  pure  MnO2  would 
oxidize  1.2874  grammes  of  Fe,  equal  to  nearly  6.5  grammes  of 
ferrous  sulphate,  -or  more  than  9  grammes  of  ammonio-ferrous 
sulphate.  Transfer  the  2-gramme  portion  to  the  dish,  add  a  large 
amount  of  water  and  about  5  c.c.  HC1,  and  pour  in  3  grammes  of 
zinc  dissolved  in  10  c.c.  H2SO4  diluted  with  enough  water  to  dis- 
solve the  sulphate  of  zinc  readily.  Titrate  with  the  standard  solu- 
tion of  permanganate  or  bichromate  of  potassium  in  the  usual  way, 
and  calculate  the  amount  of  iron  in  i  gramme  of  the  ferrous  salt 
used.  Weigh  into  the  flask  A,  Fig.  90,  page  218,  I  gramme  of  the 
finely-ground  ore,  and  add  to  it  the  larger  portion  of  the  ferrous 
salt  previously  weighed  out.  Connect  the  flask  as  in  Fig.  91,  and 
pass  in  a  current  of  CO2  until  the  air  has  been  driven  out.  Now 
pour  into  the  flask  A,  by  means  of  a  small  funnel  attached  to  B, 
10  c.c.  HC1  and  30  c.c.  water,  reconnect  the  CO2  apparatus,  and 
while  the  current  of  CO2  is  passing  dissolve  the  ore,  heating  the 


238  ANALYSIS   OF  IRON  ORES. 

flask,  and  shaking  it  from  time  to  time  as  necessary.  When  the 
ore  is  all  decomposed,  stop  the  current  of  CO2  for  a  moment, 
remove  the  light,  and  allow  the  water  in  E  to  flow  back  into  the 
flask  A.  Transfer  the  solution  to  the  dish,  add  3  grammes  zinc 
dissolved  in  H2SO4,  and  titrate  it  with  the  standard  solution. 
From  the  titration  of  the  ferrous  salt  calculate  the  amount  of 
Fe  in  the  amount  used  in  the  solution  of  the  ore,  and  subtract 
from  this  the  amount  found  by  this  last  titration ;  the  difference 
is  the  weight  of  Fe  oxidized  by  the  chlorine  liberated  from 
the  MnO2  in  the  ore.  Then,  as  112  parts  of  Fe  correspond  to 
87  parts  of  MnO2,  multiply  the  above  weight  of  iron  by  87 
and  divide  by  112,  and  the  result  is  the  weight  of  MnO2  in 
the  ore. 
Calculation  The  total  Mn  having  been  determined  by  one  of  the  methods 

of  MnO 

and  previously   given,  subtract  from  it  the  amount  of  Mn  as  MnO2 

(found  by  multiplying  the  weight  of  MnO2  by  .63218),  and  cal- 
culate the  difference  to  MnO  by  multiplying  by   1.2909. 


DETERMINATION  OF  SILICA,  ALUMINA,  LIME, 
MAGNESIA,  OXIDE  OF  MANGANESE,  AND 
BARYTA. 

Treatment  of  iron  ores  with  HC1  leaves  a  residue  which  only 
residue  in  very  rare  instances  consists  of  silica  alone,  being  usually  sili- 
cates  of  aluminium,  calcium,  and  magnesium,  mixed  with  an 
excess  of  silica.  These  silicates  are  often  much  more  complicated, 
and  contain,  besides  the  substances  enumerated  above,  protoxide 
of  iron,  soda,  potassa,  and  oxide  of  manganese.  With  these  sili- 
cates are  occasionally  found  titanic  acid,  titaniferous  iron,  chrome 
iron  ore,  sulphate  of  barium,  and  ferrous  sulphide,  besides  organic 
matter,  and  sometimes  graphite.  As  this  residue  must  be  fused 
with  Na2CO3  in  order  to  decompose  it,  and  the  introduction  of 


DETERMINATION  OF  SILICA,   ALUMINA,   ETC.  239 

sodium  salts  into  the  main  solution  is  not  desirable,  the  two  por- 
tions of  the  ore  (the  soluble  and  the  insoluble  in  HC1)  should  be 
analyzed  separately. 

Weigh  i  gramme  of  ore  into  a  No.  I  beaker,  add  15  c.c.  HC1, 
cover  with  a  watch-glass,  and  digest  at  a  gentle  heat  until  the  ore 
appears  to  be  quite  decomposed,  add  a  few  drops  of  HNO3,  heat 
until  the  action  has  ceased,  and  then  wash  off  the  cover  with  a 
fine  jet  of  water,  and  evaporate  to  dryness.  Redissolve  in  HC1, 
and  evaporate  to  dryness  a  second  time  to  render  all  the  silica 
insoluble.  Redissolve  in  10  c.c.  HC1  and  30  c.c.  water,  filter,  solution  of 
transfer  all  the  residue  to  the  filter  (a  small  ashless  filter)  with  a 
fine  jet  of  cold  water,  using  a  "policeman"  to  detach  any  ad- 
hering particles  from  the  beaker,  and  wash  the  filter  with  a  little 
HC1  and  plenty  of  cold  water.  Allow  the  filtrate  and  washings 
to  run  into  a  No.  5  beaker,  and  ignite  and  weigh  the  residue  as 
"Insoluble  Silicious  Matter" 

Add  to  the  insoluble  matter  in  the  crucible  about  ten  times  its  Analysis 
weight  of  pure  dry  Na2CO3  and  fuse  it.     Run  the  fusion  well  up 


on  the  sides  of  the  crucible  and  treat  it  with  hot  water.     Wash  it     silicious 

matter. 

out  into  a  platinum  dish,  dissolve  any  particles  adhering  to  the 
crucible  in  HC1,  and  add  this  to  the  solution  in  the  dish.  Acidu- 
late with  HC1,  evaporate  to  dryness,  moisten  with  HC1  and  water, 
evaporate  to  dryness  a  second  time  to  render  silica  insoluble,  then 
pour  into  the  dish  5  c.c.  HC1  and  15  c.c.  water,  and  stand  it  in  a 
warm  place  for  some  time.  Dilute  with  about  20  c.c.  water,  filter 
on  a  small  ashless  filter,  wash  well  with  hot  water,  receiving  the 
filtrate  and  washings  in  a  small  beaker,  dry,  ignite,  and  weigh. 
Treat  the  ignited  precipitate  with  HF1  and  a  drop  or  two  of 
H2SO4,  evaporate  to  dryness,  ignite,  and  weigh  again.  The  differ-  SiOa< 
ence  between  the  two  weights  is  SiO2.  If  the  difference  between 
the  last  weight  and  the  weight  of  the  empty  crucible  is  more  than 
a  milligramme  or  two,  the  residue  must  be  examined  and  its  nature 


determined.     This  residue  may  consist  of  titanic  acid,  sulphate  of     from  HFl 

and  H2S04 

barium,  alumina,  or  sulphate  of  sodium  (from  imperfect  washing     treatment 


240 


ANALYSIS   OF  IRON  ORES. 


of  the  silica).     If  it  is  titanic  acid  or  alumina,  the  weight  must  be 

added  to  the  weights  of  the  A12O3,  etc. 

Return  the  filtrate  from  the  SiO2  to  the  dish  in  which  it  was 

previously  contained,  heat  to  boiling,  add  a  few  drops  of  bromine- 
Ai2o3,  etc.     water  and  an  excess  of  NH4HO,  boil  until  it  smells  but  faintly 

of  NH3,  filter    on    a    small    ashless    filter,    wash    well    with    hot 
Possible        water,  dry,  ignite,  and   weigh  as   A12O3,  etc.      Besides  alumina 

constit- 
uents of      this   precipitate   may   contain    titanic    acid,   sesquioxide   of  chro- 

dpStatT     mium,  sesquioxide  of  iron,  oxide  of  manganese,  and  phosphoric 
acid. 

Return  the  filtrate  from  this  precipitate  to  the  dish,  evaporate 
down  to  about  100  c.c.,  add  oxalate  of  ammonium  and  ammonia, 
boil  for  a  few  minutes,  allow  the  precipitate  to  settle,  filter  on 
a  small  ashless  filter,  ignite  finally  for  five  minutes  over   a  blast- 
Cao.  lamp,  and  weigh  as  CaO.      To  the  filtrate  from  the  oxalate  of 

calcium  add  microcosmic  salt  and  about  one-third  the  volume 
of  the  solution  of  ammonia,  cool  in  ice-water,  stir  vigorously 
several  times,  and  allow  to  stand  overnight  so  that  the  precipi- 
tated Mg2(NH4)2P2O8  may  settle  properly,  filter,  wash  with  water 
containing  one-third  its  volume  of  ammonia  and  about  100 
grammes  of  nitrate  of  ammonium  to  the  litre,  ignite  carefully, 
and  weigh.  Dissolve  the  precipitate  in  the  crucible  in  a  little 
water  containing  from  5  to  10  drops  HC1,  filter  through  a  small 
MgO.  ashless  filter,  which  dry,  ignite,  and  weigh.  The  difference 

between    the    two   weights    is    Mg2P2O7,    which,    multiplied   by 
.36212,  gives  the  weight  of  MgO. 

Analysis  of  When  barium  has  been  shown  to  exist  in  the  ore,  as  noted 

from  the      on  page  222,  heat  the  filtrate  from  the  Insoluble  Silicious  Matter 

^lidous"    to  boiling,  add  a  few   drops    of   H2SO4,  boil  for    a  few  minutes 

Matter-       to  allow  the  precipitate  to  settle,  filter  on  a  small   ashless  filter, 

Bao.  allowing   the  filtrate   and  washings  to  run  into  a  No.  5  beaker, 

dry,  ignite,  and   weigh   as    BaSO4,  which,  multiplied  by  .65648, 

gives  the  weight  of  BaO. 

To  the  cold  filtrate  from  the  BaSO4  add  NH4HO  until  the  solu- 


DETERMINATION  OF  SILICA,   ALUMINA,   ETC.  24! 

tion  is  nearly  neutralized,  then  add  a  solution  of  carbonate  of  am- 


lion  by 

monium  until  a  slight  permanent  precipitate  is  formed  which  fails  acetate 
to  dissolve  after  vigorous  stirring,  and  redissolve  this  by  the  care- 
ful  addition  of  HC1,  drop  by  drop,  stirring  well,  and  allowing  the 
solution  to  stand  for  a  short  time  after  each  addition  of  HC1.  As 
soon  as  the  solution  clears,  add  a  solution  of  acetate  of  ammo- 
nium, made  by  slightly  acidulating  5  c.c.  of  NH4HO  by  acetic 
acid,  dilute  to  about  600  c.c.  with  boiling  water,  and  boil  for  a 
few  minutes.  Allow  the  precipitate  to  settle,  decant  the  clear 
liquid  through  a  large  washed  German  filter,  pour  the  precipitate 
on  the  filter,  and  wash  it  two  or  three  times  with  boiling  water. 
With  the  aid  of  a  platinum  spatula  return  the  precipitate  to  the 
beaker  in  which  the  precipitation  was  made,  dissolving  any  portion 
remaining  on  the  filter  or  adhering  to  the  spatula  in  dilute  HC1, 
allowing  the  acid  to  run  into  the  beaker  containing  the  precipitate. 
Wash  the  filter  thoroughly  with  cold  water,  and  evaporate  the 
solution  and  washings  to  dryness.  Redissolve  in  dilute  HC1, 
filter  into  a  large  platinum  dish,  dilute  with  hot  water,*  heat  to 
boiling,  and  add  a  slight  excess  of  ammonia.  Boil  for  a  few 
minutes  to  make  the  precipitate  granular  and  expel  the  excess  of 
ammonia,  and  filter  on  an  ashless  filter  (using  the  filter-pump 
and  cone,  page  26,  with  very  slight  pressure,  if  practicable.  Dis- 
solve any  of  the  adhering  particles  of  the  precipitate  in  the  dish 
in  a  very  few  drops  of  HC1,  heating  the  bottom  of  the  dish 
slightly,  wash  off  the  rod  and  cover,  and  wash  down  the  sides 
of  the  dish  with  hot  water,  add  a  slight  excess  of  ammonia,  heat 
gently  until  the  precipitate  of  ferric  hydrate  separates,  wash  this 

*  The  distilled  water  used  in  the  complete  analysis  of  iron  ores  should  never  be 
heated  in  glass  vessels  for  any  length  of  time,  as  glass  is  sensibly  attacked  by  it.  An 
experiment  in  which  distilled  water  free  from  residue  was  heated  for  twelve  hours  in 
a  Bohemian  flask  showed  that  the  water  dissolved  52  milligrammes  of  solid  matter 
to  the  litre,  of  which  26  milligrammes  were  SiO2.  The  water  should  always  be  heated 
in  platinum  or  porcelain  dishes,  or  in  tin-lined  copper  flasks.  For  convenience,  the 
water  may  be  poured  into  the  washing-flasks  for  immediate  use. 

16 


242  ANALYSIS   OF  IRON  ORES. 

on  the  filter,  and  wash  the  precipitate  thoroughly  with  hot  water. 
Dry  the  filter  and  precipitate  carefully,  transfer  the  latter  to  a 
weighed  crucible,  burn  the  filter  in  a  wire,  add  the  ash  to  the 
precipitate,  and  heat  the  crucible,  keeping  it  carefully  covered, 
and  raising  the  heat  very  gradually  and  slowly  to  expel  the  last 
traces  of  moisture  from  the  precipitate  of  ferric  hydrate.  Finally 
heat  the  crucible  to  bright  redness,  and  then  to  the  highest  tem- 
perature of  the  blast-lamp  for  about  five  to  ten  minutes.  Cool, 
Fe2o3+  ignite,  and  weigh  as  Fe2O3  +  A12O3  +  P2O5  (  +  TiO2  +  Cr2O3  + 

A12O3  + 

p2o6.        As2O5). 

Add  the  filtrate  and  washings  from  the  acetate  precipitation  to 
those  from  the  precipitation  by  ammonia,  evaporate  down  to  about 
200  c.c.  in  a  platinum  dish,  filter  off  any  slight  precipitate  of  Fe2O3 
(which  must  be  ignited,  weighed,  and  the  weight  added  to  that  of 
the  Fe2O3,  etc.),  add  20  to  30  drops  of  acetic  acid,  heat  to  boil- 
ing, and  pass  a  current  of  H2S  through  the  solution  for  fifteen 
or  twenty  minutes,  keeping  the  solution  hot  during  the  passage 
of  the  gas.  Filter  off  the  precipitated  sulphides  of  copper,  zinc, 
nickel,  and  cobalt,  wash  with  H2S  water  containing  a  little  free 
acetic  acid,  and  to  the  filtrate  add  excess  of  ammonia  and  sul- 
phide of  ammonium.  Allow  the  precipitated  sulphide  of  man- 
ganese to  settle,  decant  the  clear,  supernatant  liquid  through  a 
filter,  but  before  pouring  the  precipitate  on  the  filter  remove  the 
beaker  containing  the  filtrate  and  substitute  a  clean  beaker,  for 
the  precipitate  is  almost  certain  at  first  to  run  through  the  filter. 
Wash  the  precipitate  and  filter  with  water  containing  a  little  sul- 
phide of  ammonium,  add  the  clear  filtrate  and  washings  together, 
and  stand  them  aside.  Dissolve  the  precipitate  of  sulphide  of 
manganese  on  the  filter  in  dilute  HC1,  and  wash  the  filter  thor- 
oughly with  hot  water,  receiving  the  solution  and  washings  in  a 
small  beaker.  Heat  to  boiling  to  expel  H2S,  and,  when  the  excess 
is  driven  off,  destroy  the  last  traces  with  a  little  bromine-water, 
transfer  the  solution  to  a  platinum  dish,  and  precipitate  by  micro- 
cosmic  salt  and  ammonia  as  directed  on  page  112.  Filter,  wash, 


DETERMINATION  OF  SILICA,   ALUMINA,  ETC. 

243 

ignite,  and  weigh  as  Mn2P2O7,  which,  multiplied  by  .50011,  gives 
the  weight  of  MnO.  Mno. 

Acidulate  the  filtrate  from  the  sulphide  of  manganese  with 
HC1,  boil  off  all  the  H2S,  filter  from  the  sulphur  deposited  by  this 
operation  into  a  platinum  dish,  add  an  excess  of  ammonia  and 
oxalate  of  ammonium,  filter  off,  ignite,  and  heat  at  the  highest 
temperature  of  the  blast-lamp  for  fifteen  minutes,  cool,  and  weigh 
as  CaO.  Cao. 

Precipitate  the  magnesia  in  the  filtrate  as  directed  on  page  232, 
and  determine  the  weight  of  Mg2P2O7,  which,  multiplied  by  .36212, 
gives  the  weight  of  MgO.  Mgo. 

By  adding  the  elements  determined  in  the  insoluble  portion  to 
the  similar  ones  in  the  soluble  portion,  we  get  the  total  amounts 
of  each  in  the  ore.  Thus,  we  have  from  the  above  analysis 

Si02,Fe203  +  Al203+P205+Cr203  +  Ti02  +  As205,  MnO,  CaO, 
and  MgO,  and  it  becomes,  of  course,  necessary  to  calculate  prop- 
erly the  iron  in  its  different  states  of  oxidation  and  to  determine 
the  amount  of  A12O3  in  the  ore.  It  is  much  more  accurate  to 
determine  in  separate  portions  of  the  ore  the  amounts  of  P2O5, 
As2O5,  Cr2O3,  Fe2O3,  and  TiO2  than  to  attempt  to  make  the  sepa- 
ration in  the  precipitate  obtained  in  this  portion.  Therefore, 
knowing  the  amounts  of  these  substances,  the  Fe2O3  from  the  vol- 
umetric determination  of  iron,  as  previously  described,  and  the 
amount  of  each  of  the  others  as  found  by  one  of  the  methods 
given,  add  together  the  weights  of  the  Fe2O3,  the  P2O5,  the  Cr2O3, 
the  TiO2,  and  the  As2O5  in  one  gramme  of  the  ore,  and  subtract 
the  sum  from  the  weight  of  the  precipitate  obtained  in  the  above 
analysis,  the  result  is  the  weight  of  A12O3  in  one  gramme  of  the  Ai2o3. 
ore. 

Iron  may  exist  in  an  ore  in  several  conditions,  as  Fe-jO^  as 
FeO,  as  FeS2,  as  FeAs2,  etc.  While  it  may  not  always  be  possible 
to  determine  the  exact  conditions  in  which  it  exists,  the  rule 
usually  followed  is,  after  subtracting  from  the  sulphur  existing 
as  sulphides  (page  229)  the  amount  necessary  to  form  sulphide 


244 


ANALYSIS   OF  IRON  ORES. 


Fes2. 


Feo. 


Method  for 
ores  con- 

taining 


of  copper,  sulphide  of  nickel,  etc.,  to  calculate  the  remainder  as 
FeS2  by  multiplying  the  weight  of  S  by  1.87336.  The  weight  of 
S  subtracted  from  this  gives  the  weight  of  iron  in  the  FeS2.  Now 
from  the  weight  of  FeAs2  subtract  the  weight  of  arsenic,  and 
the  result  is  the  weight  of  iron  existing  as  Fe  in  the  FeAs2.* 
Add  the  Fe  in  the  FeS2  to  the  Fe  in  the  FeAs2,  and  subtract 
this  weight  from  the  Fe  found  as  FeO,  the  remainder  calculated 
to  FeO  is  the  amount  of  FeO  in  the  ore.  Subtract  the  total 
amount  of  Fe  found  originally  by  titration  to  exist  as  FeO  from 
the  total  Fe  found  in  the  ore,  and  calculate  the  remainder  to 
Fe2O3. 

When  an  iron  ore  contains  only  a  very  small  amount  of  man- 
ganese,  the  acetate  separation  may  be  omitted  in  the  method  as 
given  above,  which  simplifies  and  shortens  the  operation  very 
materially.  In  this  event  transfer  the  filtrate  from  the  insoluble 
silicious  matter  at  once  to  a  large  platinum  dish,  heat  to  boiling, 
add  a  few  c.c.  of  bromine-water  and  then  excess  of  ammonia,  boil, 
and  filter  the  Fe2O3,  etc.,  on  an  ashless  filter,  dry,  ignite,  and 
weigh,  as  described  above.  The  manganese  will  be  in  the  pre- 
cipitate after  ignition  as  Mn3O4,  and  the  amount  calculated  from 
the  determination  of  manganese  made  in  a  separate  portion  of  the 
ore  must  be  subtracted  from  the  weight  of  the  above  precipitate 
in  calculating  the  amount  of  A12O3. 

The  lime  and  magnesia  are  determined  in  the  filtrate  from  the 
Fe2O3,  etc.,  providing,  of  course,  that  the  ore  contains  only  minute 
amounts  of  nickel,  copper,  etc. 

The  same  general  method  described  above  is  applicable  when 
the  ore  contains  quite  a  large  amount  of  titanic  acid,  so  much, 
in  fact,  as  to  cause  the  cloudiness  in  the  filtrate  from  the  insolu- 
ble silicious  matter,  as  noted  on  page  230.  Whenever  an  acetate 
separation  is  necessary  in  an  ore  of  this  character,  the  precipitate 
must  be  filtered  on  an  ashless  filter,  and  this  filter,  as  well  as  the 


All  the  weights,  of  course,  are  calculated  to  i  gramme  of  ore. 


TITANIFEROUS   ORES. 


245 


filter  containing  any  insoluble  matter  from  the  resolution  of  the 
acetate  precipitate,  must  be  ignited  and  examined  for  TiO2  by 
treating  the  residue  with  HF1  and  H2SO4,  heating  to  redness, 
fusing  with  Na2CO3,  dissolving  in  HC1  and  water,  and  precipi- 
tating by  ammonia.  The  precipitate  so  obtained  is  to  be  filtered, 
ignited,  and  the  weight  added  to  that  of  the  Fe2O3,  etc.  Ilmenite 
even,  when  very  finely  ground  in  an  agate  mortar,  is  frequently 
capable  of  being  almost  entirely  decomposed  by  HC1,  and  when 
this  is  the  case  it  is  of  advantage  to  use  this  method  of  analysis. 
It  may  be  necessary,  however,  under  certain  circumstances  to 
decompose  the  ore  at  the  start  by  fusing  with  bisulphate  of  potas- 
sium. To  carry  out  this  method,  weigh  I  gramme  of  the  ore,  Fusion  with 
which  has  been  ground  as  fine  as  possible  in  an  agate  mortar,  into  of^aL* 
a  large  platinum  crucible,  add  10  grammes  of  pure  bisulphate  of 
potassium,*  and  heat  the  crucible,  carefully  covered,  over  a  very 
low  light  until  the  bisulphate  is  melted.  It  is  necessary  to  watch 
this  operation  most  carefully,  for  the  bisulphate  has  a  strong 
tendency  to  boil  over,  and  only  unremitting  attention  on  the  part 
of  the  analyst  will  prevent  the  loss  of  the  analysis.  It  is  well  at 
the  start  to  stand  by  the  crucible  and  raise  the  lid  slightly  at  very  Precautions 
short  intervals  to  watch  the  condition  and  progress  of  the  fusion. 
The  lid  should  be  held  just  over  the  crucible  and  in  a  horizontal 
position,  otherwise  the  particles  which  have  spirted  on  it  from  the 
mass  in  the  crucible  may  run  to  the  edge  of  the  lid  and,  when  the 
latter  is  replaced,  down  the  outside  of  the  crucible.  Raise  the 
heat  very  gradually,  keeping  the  mass  just  liquid  and  the  tem- 
perature at  the  point  at  which  slight  fumes  of  SO3  are  given  off 
when  the  lid  is  raised,  until  the  bottom  of  the  crucible  is  dull  red. 
When  the  ore  is  completely  decomposed,  remove  the  light,  take 
off  the  lid  of  the  crucible,  and  incline  the  latter  at  such  an  angle 
that  the  fused  mass  may  run  together  on  one  side  of  the  crucible 
and  as  near  the  top  as  possible.  Allow  it  to  cool  in  this  position ; 

*  See  page  49.  • 


246 


ANALYSIS   OF  IRON  ORES. 


Solution  of 
the  fused 
mass. 


SiO2. 


Treatment 
of  impure 
precipitate 
of  TiO2. 


TiO2. 


Fe2O3  and 
A12O3  car- 
ried down 
with  first 
precipitate 
of  Ti02. 


when  cold  it  is  easily  detached  from  the  crucible.  Place  the 
crucible  and  lid  in  a  No.  4  beaker  half  full  of  cold  water,  and  the 
fused  mass  in  the  little  basket,  as  shown  in  Fig.  76,  page  165. 
Pour  into  the  beaker  enough  strong  aqueous  solution  of  sulphur- 
ous acid  to  raise  the  liquid  to  the  top  of  the  basket,  and  allow 
the  fusion  to  dissolve,  which  may  require  twelve  hours.  Wash  off 
with  a  jet  of  cold  water,  and  remove  the  basket,  the  crucible,  and 
lid,  stir  the  liquid,  which  should  smell  strongly  of  SO2,  and  allow 
the  insoluble  matter  to  settle.  Filter  on  an  ashless  filter,  wash 
well  with  cold  water,  dry,  ignite,  and  weigh.  Treat  with  HF1  and 
2  or  3  drops  of  H2SO4,  evaporate  to  dryness,  ignite,  and  weigh. 
The  difference  between  the  weights  is  SiO2.  If  any  appreciable 
residue  remains  in  the  crucible,  fuse  with  a  little  Na2CO3,  treat 
with  H2SO4,  and  add  to  the  main  filtrate.  To  the  main  filtrate, 
which  should  be  quite  colorless  and  which  should  smell  strongly 
of  SO2,  add  a  clear  filtered  solution  of  20  grammes  of  acetate  of 
sodium  and  one-sixth  of  its  volume  of  acetic  acid,  1.04  sp.  gr., 
heat  to  boiling,  and  boil  for  a  few  minutes.  Allow  to  settle,  filter 
on  an  ashless  filter,  wash  thoroughly  with  hot  water  containing 
one-sixth  its  volume  of  acetic  acid,  and  finally  with  hot  water,  dry, 
ignite,  and  weigh  as  TiO2.  This  precipitate,  however,  may  not  be 
quite  pure,  as  small  amounts  of  ferric  oxide  and  alumina  may  be 
carried  down  with  it.  The  best  plan  to  pursue  is  to  fuse  with 
Na2CO3,  dissolve  in  water,  filter,  wash,  dry,  and  fuse  the  insoluble 
titanate  of  sodium,  etc.,  with  Na2CO3,  treat  the  cooled  mass  in  the 
crucible  with  H2SO4,  and  precipitate  and  determine  the  TiO2  as 
directed  above.  The  two  filtrates  from  the  treatment  of  the  first 
precipitate  of  TiO2  may  contain  a  little  oxide  of  iron  and  alumina. 
To  recover  this,  boil  down  the  last  filtrate  until  the  greater  part  of 
the  sulphurous  acid  has  been  driven  off,  add  bromine-water  to  oxi- 
dize the  iron,  acidulate  the  aqueous  filtrate  from  the  carbonate  of 
sodium  fusion  with  H2SO4,  add  it  to  this  solution,  boil  the  united 
solutions  down  in  a  platinum  dish  to  a  convenient  volume,  and  add 
a  slight  excess  of  ammonia.  Boil  the  solution  until  it  smells 


DETERMINATION  OF  SILICA.  247 

faintly  but  decidedly  of  ammonia,  filter  off,  and  wash  slightly. 
Redissolve  the  precipitate  in  HC1,  and  reprecipitate  by  ammonia, 
filter,  wash,  ignite,  and  weigh  as  Fe2O3  +  A12O3,  to  be  added  to  the 
main  precipitate.  Boil  the  main  filtrate  and  washings  down  in  a 
large  platinum  dish  after  adding  enough  bromine-water  to  oxidize 
all  the  iron,  add  HC1  from  time  to  time  when  necessary  to  keep 
the  iron  in  solution,  and,  when  reduced  to  a  convenient  bulk, 
nearly  neutralize  by  ammonia,  and  boil.  Filter  off  and  wash  the 
precipitate  two  or  three  times,  redissolve  and  reprecipitate  by 
ammonia,  filter,  wash,  dry,  ignite,  and  weigh  as  Fe2O3  +  A12O3  +  F^OS* 
P2O5.  Fuse  this  precipitate  for  a  long  time  and  at  a  high  tempera-  P2o63 
ture  with  Na2CO3,  dissolve  in  water,  wash  by  decantation,  redis- 
solve the  residue  of  Fe2O3,  etc.,  in  HC1,  and  determine  the  iron  by 
titration.  Determine  the  alumina  by  difference,  the  P2O5  being 
determined  in  a  separate  portion.  In  the  filtrate  from  the  Fe2O3  + 
A12O3  +  P2O5  determine  manganese,  lime,  and  magnesia  in  the  MnO.CaO, 
usual  way. 


DETERMINATION    OF   SILICA. 

When  silica  alone  is  wanted  in  an  ore  a  more  rapid  method  is 
sometimes  desirable.     In  this  case  dissolve  I  gramme  of  the  ore  in 
HC1,  evaporate  to  dryness,  redissolve  in  dilute  HC1,  filter  on  an 
ashless  filter,  wash,  dry,  ignite,  and  weigh  the  insoluble  silicious 
matter.      Treat  this  in  the  crucible  with  HF1  and  a  few  drops  of 
H2SO4,  evaporate  to  dryness,  ignite,  and  weigh.     It  is  evident  now 
that  if  the  insoluble  silicious  matter  contains  calcium,  magnesium,  Lossbyvoi- 
potassium,  or  sodium,  the  loss  of  weight,  which  in  the  absence  of      Wuh  HFI 
these  elements  would  represent  the  SiO2  volatilized  as  fluoride  of      ^504. 
silicon,  will  be  decreased  by  the  amount  of  sulphuric  acid  which, 
uniting  with  these  elements,  remains  as  a  part  of  the  residue  in  the 
crucible.     It  is  a  simple  operation,  however,  to  fuse  this  residue 


248 


ANALYSIS   OF  IRON  ORES. 


Si02. 


Separation 
by  citric 
acid,  am- 
monia, 
and  sul- 
phide ot 
ammo- 
nium. 


Danger  of 
loss  by 
spirting 


with  Na2CO3,  dissolve  in  water,  acidulate  with  HC1,  heat  to  boil- 
ing, add  solution  of  BaCl2  and  filter  off,  and  weigh  the  precipitated 
BaSO4.  This  being  accomplished,  calculate  the  amount  of  SO3, 
and  add  its  weight  to  the  loss  by  volatilization.  The  result  is  the 
weight  of  SiO2.  When  the  ore  contains  appreciable  amounts  of 
sulphate  of  barium  this  method  is  not  admissible. 

Separation  of  Alumina  from  Ferric  Oxide. 
Besides  the  indirect  method  for  determining  alumina,  it  is 
sometimes  necessary  or  convenient  to  make  a  direct  separation. 
The  method  usually  taken,  the  iron  and  alumina  being  in  solution 
in  HC1,  is  as  follows :  Add  to  the  solution  about  five  times  the 
weight  of  the  oxides,  of  citric  acid  (tartaric  acid  may  be  used,  but, 
as  it  is  liable  to  contain  alumina,  citric  acid  is  preferable)  and 
excess  of  ammonia.  If  the  solution  remains  clear,  heat  to  boiling, 
and  add  a  fresh  solution  of  sulphide  of  ammonium  until  all  the 
iron  is  precipitated.  If  the  solution  does  not  remain  clear  on  the 
addition  of  ammonia,  acidulate  with  HC1,  add  more  citric  acid,  and 
then  excess  of  ammonia.  Allow  the  sulphide  of  iron  to  settle, 
decant  the  clear  liquid  through  a  washed  filter,  throw  the  precipi- 
tate on  the  filter,  and  wash  it  well  with  water  containing  sulphide 
of  ammonium,  changing  the  beaker  into  which  the  washings  run 
before  each  addition  of  wash-water,  and  keeping  the  funnel  well 
covered  with  a  watch-glass.  Unite  the  filtrate  and  washings,  acidu- 
late with  HC1,  boil  until  the  precipitated  sulphur  agglomerates, 
filter  into  a  platinum  dish,  and  evaporate  to  dryness.  Heat  care- 
fully until  the  chloride  of  ammonium  is  volatilized  and  there 
remains  in  the  dish  a  mass  of  carbonaceous  matter  from  the 
decomposition  of  the  citric  acid.  The  expulsion  of  the  last  traces 
of  water  from  the  chloride  of  ammonium  nearly  always  causes  loss 
by  spirting,  but  the  difficulty  may  be  entirely  avoided  by  placing 
the  dish  in  one  of  the  holes  of  the  air-bath  overnight,  after  having 
lightly  coated  the  upper  edge  of  the  dish  with  paraffine  or  grease 
to  prevent  the  chloride  of  ammonium  from  creeping  over  the  top. 


SEPARATION  OF  ALUMINA   FROM  FERRIC   OXIDE.  249 

This  long  heating  expels  the  last  traces  of  water  without  the  least 
disturbance,  and  the  dish  may  be  at  once  placed  over  a  Bunsen 
burner,  and  the  mass  in  it  decomposed  without  fear  of  loss. 
Transfer  the  carbonaceous  matter  to  a  crucible,  wiping  out  the 
dish  carefully  with  filter-paper,  and  placing  these  in  the  crucible 
also.  Burn  off  the  carbon  in  the  crucible,  fuse  the  residue  with 
Na2CO3  and  a  little  NaNO3,  treat  with  water,  transfer  to  a  platinum 
dish,  dissolve  any  adhering  particles  in  the  crucible  in  HC1,  add 
this  to  the  solution  in  the  dish,  with  enough  HC1  to  acidulate 
it,  heat  to  boiling  after  diluting,  add  a  slight  excess  of  ammonia, 
boil  until  the  solution  smells  but  faintly  of  NH3,  filter,  wash 
thoroughly,  ignite,  and  weigh  as  A12O3.  This  precipitate  will  AiaO3. 
contain  any  P2O5,  Cr2O3,  and  TiO2  that  may  have  been  in  the 
original  solution.  They  may  be  separated  by  the  methods  given  impurities, 
on  page  189  et  seq.  It  is  liable  to  contain  also  a  little  iron, 
which  is  almost  invariably  held  in  solution  by  the  sulphide  of 
ammonium. 

Dissolve  the  precipitate  of  ferrous  sulphide  on  the  filter  in 
dilute  hot  HC1,  allow  the  solution  and  washings  to  run  into  the 
beaker  in  which  the  precipitation  was  made,  add  a  little  HNO3, 
evaporate  to  dry  ness,  redissolve  in  as  little  dilute  HC1  as  possible, 
filter  into  a  platinum  dish,  dilute,  precipitate  by  ammonia,  filter, 
wash,  dry,  ignite,  and  weigh  as  Fe2O3.  Fe2o3. 

Rose  *  suggested  the  method  based  on  the  solubility  of  alu-  separation 
mina  in  caustic  potassa  or  soda.     When  the  iron  and  alumina  are     pou«a  <* 
in  solution,  evaporate  until  syrupy  in  a  platinum  dish,  add  a  strong 
solution  of  caustic  soda  or  potassa  until  the  solution  is  strongly 
alkaline,  and  then  add  a  large  excess  of  the  precipitant,  and  boil 
for  ten  or  fifteen  minutes  ;    or,  pour  the  nearly  neutral  solution  of 
the  chlorides  into  a  boiling  solution  of  caustic  soda  or  potassa  in 
a  platinum   or  silver  dish,  in  a  thin  stream,  stirring  continually. 
Filter,  wash  with  hot  water,  carefully  acidulate  the  filtrate  with 

*  Chimie  Anal.  Quant.  (French  ed.),  page  148. 


250 


ANALYSIS   OF  IRON  ORES. 


Objection 
method. 


current  of 
after  ^e- 


Rose's  mod- 

ification. 


Separation 

by  hypo- 
sulphite of 


HC1,  and  precipitate  the  alumina  by  ammonia,  filter,  wash,  dis- 
solve in  HC1,  evaporate  to  dryness  to  get  rid  of  SiO2,  redissolve, 
filter,  and  determine  as  usual.  As  the  Fe2O3  precipitated  by  caus- 
tic soda  or  potassa  always  contains  alkali,  it  must  be  dissolved  in 
HC1,  precipitated  by  ammonia,  filtered,  and  weighed  in  the  usual 
manner. 

Rose  also  suggested  fusing  the  finely-ground  ignited  oxides 
in  a  silver  crucible  with  potassium  or  sodium  hydrate  ;  but  this 
method,  as  well  as  the  other,  is  open  to  the  objection  that  it  is 
almost  impossible  to  get  caustic  soda  or  potassa  that  does  not  con- 
tain alumina,  and  generally  there  would  be  more  in  the  reagent 
than  in  the  ore. 

Rivot  suggested  the  following  method  :  After  weighing  the 
ignited  oxides  of  iron  and  aluminium,  grind  them  very  fine,  and 
weigh  them  into  a  porcelain  or  platinum  boat.  Place  the  boat 
in  a  porcelain  or  platinum  tube,  and  heat  to  redness  in  a  cur- 
rent  of  hydrogen  gas  until  no  more  H2O  appears  to  come  off. 
Replace  the  hydrogen  by  a  stream  of  HC1  gas,  reheat  the  tube, 
and  continue  the  current  as  long  as  ferric  chloride  is  given  off. 
Remove  the  boat,  and,  if  the  residue  is  not  white,  repeat  the  opera- 
tion. Weigh  the  remaining  A12O3,  and  calculate  from  the  amount 
of  the  oxides  used  the  total  amount  in  the  ore. 

Rose  modified  this  method  by  substituting  a  crucible  and  tube 
for  the  boat,  etc.  The  apparatus  as  he  used  it  is  the  same  as 
that  described  for  the  determination  of  manganese  as  sulphide, 
page  114. 

Wohler  suggested  the  method  of  separating  iron  and  alumina 
by  boiling  the  nearly  neutral  solution  with  an  excess  of  hypo- 
sulphite of  sodium.  The  following  modification  of  this  method* 
appears  to  give  excellent  results,  and  has  the  advantage  of  doing 
away  with  a  subsequent  separation  of  P2O5  in  those  cases  in  which 
it  has  not  been  determined  in  another  portion.  The  Fe2O3  and 


*  Communicated  to  me  by  Mr.  S.  Peters  in  1879. 


DETERMINATION  OF  NICKEL,  COBALT,  ETC.  251 

A12O3  from  I  gramme  of  ore  being  in  solution  in  HC1,  dilute  to  Peters's 
400  or  500  c.c.  with  cold  water,  and  add  ammonia  until  the  solu-  tion. 
tion  becomes  dark  red  in  color,  but  contains  no  precipitate.  Now 
add  3.3  c.c.  HC1,  1.2  sp.  gr.,  and  2  grammes  phosphate  of  sodium, 
dissolved 'in  water  and  filtered;  stir  until  the  precipitate  formed  is 
dissolved  and  the  solution  becomes  perfectly  clear  again.  Add 
now  10  grammes  of  hyposulphite  of  sodium,  dissolved  in  water 
and  filtered  if  necessary,  and  15  c.c.  of  acetic  acid,  1.04  sp.  gr., 
heat  to  boiling,  boil  fifteen  minutes,  filter  as  rapidly  as  possible  on 
an  ashless  filter,  wash  thoroughly  with  hot  water,  dry,  ignite  in  a 
porcelain  crucible,  and  weigh  as  A1PO4,  which,  multiplied  by  .41847, 
gives  the  weight  of  A12O3.  It  is  necessary  in  burning  off  the  pre- 
cipitate to  raise  the  heat  very  carefully  until  all  the  carbon  has 
been  burned  off,  as  the  A1PO4  may  fuse  and  make  it  almost 
impossible  to  burn  off  the  carbon. 


DETERMINATION     OF     NICKEL,     COBALT,     ZINC, 
AND  MANGANESE. 

For  the  determination  of  these  elements  use  3  grammes  of  Solution  of 
ore,  dissolve  in  HC1,  add  a  little  HNO3  or  KC1O3  to  oxidize  any 
FeO  in  the  ore,  evaporate  to  dryness,  redissolve  in  HC1,  and  evap- 
orate a  second  time  if  necessary  to  get  rid  of  all  HNO.  As  noted 
on  page  235,  when  the  ore  contains  much  organic  matter,  dissolve 
in  HC1  (if  there  is  much  gelatinous  silica,  evaporate  to  dryness  or 
the  filtration  will  be  much  retarded),  filter,  add  HNO3  or  KC1O3, 
evaporate  to  dryness,  redissolve  in  HC1,  and  evaporate  a  second 
time  if  necessary,  redissolve  in  10  c.c.  HC1  and  20  c.c.  water,  dilute, 
filter  into  a  No.  6  beaker,  and  proceed  exactly  as  directed  for  the 
determination  of  manganese  in  iron  and  steel,  page  1 10  et  seq.y 
until  the  precipitate  by  H2S  is  obtained  and  filtered  off.  Deter- 


252  ANALYSIS   OF  IRON  ORES. 

mine  the  manganese,  if  desired,  in  the  filtrate,  as  directed  on  page 

MnO.  112,  and  calculate  to  MnO. 

Dry  and  ignite  the  precipitated  sulphides  of  nickel,  cobalt, 
zinc,  copper,  lead,  etc.,  in  a  porcelain  crucible,  transfer  to  a  small 
beaker,  and  dissolve  in  HC1,  with  the  addition  of  a  drop  or  two  of 
HNO3.  Evaporate  to  dryness,  redissolve  in  10  to  20  drops  HC1, 
dilute  to  50  or  60  c.c.,  heat  to  boiling,  and  pass  a  current  of  H2S 

Sulphides      through  the  boiling  solution.     Filter  off  the  precipitated  sulphides 

of  copper, 

lead,  etc.  of  copper,  lead,  etc.,  and  wash  with  water  containing  H2S.  Evap- 
orate to  dryness  the  filtrate,  which  contains  only  nickel,  cobalt, 
and  zinc.  To  the  dry  salts  in  the  bottom  of  the  beaker  add  2 
drops  of  strong  HC1,  dilute  to  150  c.c.  with  cold  water,  and  pass 
H2S  through  the  solution  until  it  is  thoroughly  saturated  with  the 
gas.  If  a  white  precipitate  forms,  it  is  sulphide  of  zinc.  Allow 
to  stand  several  hours,  filter,  wash  with  H2S  water  (the  sulphide 
of  zinc  has  a  tendency  to  pass  through  the  filter,  and  consequently 
the  beaker  into  which  the  filtrate  is  received  must  be  changed 
before  the  precipitate  is  poured  on  the  filter),  dry,  and  ignite  the 
precipitate.  Heat  it  several  times  with  carbonate  of  ammonium 
to  drive  off  any  sulphuric  acid  that  may  have  been  formed  by  the 
Zno.  ignition,  cool,  and  weigh  as  ZnO.  The  precipitate  is  greenish 

white  while  hot  and  yellowish  white  when  cold.  If  it  should 
carry  down  a  little  cobalt  from  the  solution,  the  ignited  precipitate 
of  ZnO  is  green  when  cold.  Pass  H2S  through  the  filtrate  from 
the  ZnS  again,  and,  if  no  further  precipitate  appears,  add  a  few 
drops  of  a  solution  of  .5  gramme  of  acetate  of  sodium  in  10  c.c. 
water.  If  this  occasions  a  white  precipitate,  filter  it  off,  after 
standing,  as  in  the  first  instance;  but  if  the  precipitate  is  black 
(as  it  is  almost  certain  to  be  if  the  instructions  given  above  are 
strictly  followed),  add  the  rest  of  the  acetate  of  sodium  solution, 
heat  the  solution  to  boiling,  while  the  passage  of  the  H2S  is  con- 
tinued, allow  the  precipitate  to  settle,  filter  it  off,  ignite  it,  and 
treat  it  as  directed  for  the  separation  and  determination  of  nickel 
and  cobalt,  page  184  et  seq. 


DETERMINATION  OF  COPPER,  LEAD,  ETC.  253 

DETERMINATION  OF  COPPER,  LEAD,  ARSENIC, 
AND  ANTIMONY. 

Treat  10  grammes  of  the  very  finely  ground  ore  with  50  c.c. 
HC1,  add  a  little  KC1O3  from  time  to  time,  and  increase  the  heat 
gradually  until  the  ore  is  perfectly  decomposed.  Dilute,  filter  into 
a  No.  5  beaker,  deoxidize  with  bisulphite  of  ammonium,  as  directed 
on  page  82,  drive  off  the  excess  of  SO2,  and  pass  H2S  through  the 
solution  for  fifteen  or  twenty  minutes.  Allow  the  solution  to  stand 
for  some  hours  until  the  precipitate  has  settled  completely  and  the 
solution  smells  but  faintly  of  H2S.  Filter  on  a  thin  felt  on  the 
Gooch  crucible  or  small  cone,  wash  with  cold  water,  and  suck  dry. 
Transfer  the  felt  and  precipitate  to  a  small  beaker,  using  a  little 
asbestos  wad  in  the  forceps  to  wipe  off"  any  adhering  precipitate 
from  the  large  beaker  and  the  crucible  or  cone,  and  digest  it  with  a 
few  c.c.  of  a  colorless  solution  of  sulphide  of  potassium.  Dilute  to  Separation 
about  100  c.c.,  filter  on  another  felt,  and  wash  with  water  contain- 
ing  a  little  sulphide  of  potassium.  The  solution  contains  the  sul- 
phides  of  arsenic  and  antimony  dissolved  in  sulphide  of  potassium, 
while  the  sulphides  of  copper  and  lead  remain  in  the  felt.  Return 
the  felt  with  the  precipitate  to  the  beaker  from  which  they  were 
filtered,  and  digest  with  HC1,  with  the  addition  of  HNO3,  until  all 
the  black  sulphides  are  dissolved,  dilute  with  a  little  hot  water,  and 
filter.  Evaporate  the  filtrate,  after  adding  a  few  drops  of  H2SO4, 
until  fumes  of  SO3  are  evolved,  allow  to  cool,  dilute  with  25  c.c. 
cold  water,  add  one-half  its  bulk  of  alcohol,  allow  to  settle,  filter 
the  precipitated  PbSO4  on  the  Gooch  crucible,  wash  with  alcohol 
and  water,  heat  carefully  over  a  low  light,  and  weigh.  Treat  the 
precipitate  in  the  felt  under  a  slight  pressure  with  a  strongly  am- 
moniacal  solution  of  citrate  of  ammonium,  to  dissolve  the  PbSO4, 
wash  with  hot  water,  and  weigh.  The  difference  between  the  two 
weights  is  PbSO4,  which  multiplied  by  .68298  gives  the  weight 
of  Pb,  or  multiplied  by  78879  gives  the  weight  of  PbS.  PbandPbs. 

Evaporate  the  filtrate  from  the    PbSO4  until  the  alcohol  is 


254 


ANALYSIS   OF  IRON  ORES. 


Cu  and 
Cu2S. 


Solution  of 
sulphides 
of  arsenic 
and  anti- 
mony by 
HC1  and 
KC103. 


Mg2(NH4)2 

As2 
Aq. 


and 
FeAs2. 


driven  off  and  the  solution  reduced  to  a  convenient  bulk,  transfer 
to  a  platinum  crucible,  and  precipitate  the  copper  on  the  small 
platinum  cylinder  by  the  battery,  page  182.  The  weight  of  Cu 
multiplied  by  1.25284  gives  the  weight  of  Cu2S. 

Acidulate  the  nitrate  of  sulphide  of  potassium  containing  ar- 
senic and  antimony  in  solution  with  HC1,  and  allow  to  stand  in  a 
warm  place  until  all  the  H2S  has  been  driven  off  and  the  sulphides 
of  arsenic  and  antimony  mixed  with  the  excess  of  sulphur  have 
settled  completely.  Filter  on  a  thin  felt,  wash  with  warm  water, 
then  with  alcohol,  and  finally  with  bisulphide  of  carbon,  to  dis- 
solve the  excess  of  S.  Transfer  the  felt  and  precipitate  to  a  small 
beaker,  add  5  c.c.  HC1  and  a  few  crystals  of  KC1O3.  Digest  at 
a  low  temperature  for  some  time,  adding  occasionally  a  small  crys- 
tal of  KC1O3,  finally  heat  a  little,  but  not  to  a  sufficiently  high 
degree  to  fuse  any  little  particles  of  separated  sulphur,  keeping  the 
liquid  always  full  of  the  products  of  decomposition  of  the  KC1O3. 
When  all  the  sulphides  of  arsenic  and  antimony  are  dissolved, 
dilute  with  about  20  c.c.  of  warm  water,  and  add  a  few  small 
crystals  of  tartaric  acid  to  keep  the  antimony  in  solution.  Filter 
from  the  asbestos,  using  as  little  wash-water  as  possible  in  order 
to  keep  down  the  volume  of  the  solution,  add  a  slight  excess  of 
ammonia  to  the  filtrate,  and  if  it  remains  clear  5  c.c.  of  magnesia 
mixture  and  one-third  the  volume  of  the  solution  of  NH4HO. 
Cool  in  ice-water,  and  stir  vigorously  from  time  to  time  to  pre- 
cipitate the  Mg2(NH4)2As2O8-h  Aq. 

Allow  to  stand  overnight,  filter,  and  determine  the  arsenic 
as  directed  on  page  196.  If  the  acid  solution  above  mentioned 
becomes  cloudy  upon  the  addition  of  NH4HO,  acidulate  care- 
fully with  HC1,  and  add  a  little  more  tartaric  acid.  Then  proceed 
as  above  directed.  The  weight  of  As  calculated  from  the  amount 
of  Mg2As2O7,  multiplied  by  1.373,  gives  the  weight  of  FeAs2. 

Acidulate  the  filtrate  from  the  Mg2(NH4)2As2O8  -f  Aq,  which 
contains  none  of  the  washings,  with  HC1  so  that  the  solution  is 
just  acid  to  test-paper,  dilute  with  hot  water  to  about  250  c.c., 


DETERMINATION  OF   THE  ALKALIES.  2$$ 

and  pass  H2S  into  the  solution,  heating  it  gradually  to  boiling. 
Drive  off  the  excess  of  H2S  with  a  current  of  CO2,  filter  on  a  felt 
in  the  Gooch  crucible,  wash  with  water,  alcohol,  and  finally  with 
bisulphide  of  carbon  to  dissolve  any  free  sulphur,  dry  carefully, 
heat  to  a  temperature  slightly  above  100°  C,  and  weigh  as  Sb2S3. 
For  the  very  small  amounts  of  antimony  that  are  found  in  iron 
ores  this  method  is  sufficiently  exact.  The  weight  of  Sb2S3  mul-  sb2s3and 
tiplied  by  .71390  gives  the  weight  of  Sb. 


DETERMINATION    OF  THE   ALKALIES. 

As  a  rule,  the  alkalies  in  iron  ores  are  found  exclusively  in  the 
insoluble  silicious  matter,  and  when  the  sum  of  the  weights  of  the 
SiO2,  A12O3  etc.,  CaO,  and  MgO  in  the  insoluble  silicious  matter 
falls  much  below  the  weight  of  the  latter,  it  is  always  well  to  look 
for  alkalies. 

Dissolve  3  grammes  of  the  ore  in  HC1,  evaporate  to  dryness, 
redissolve  in  10  c.c.  HC1  +  2O  c.c.  water,  dilute,  and  filter  into  a 
platinum  dish.     Ignite  the  insoluble  residue,  treat  it  in  the  crucible  Treatment 
with  HF1  and  10  to  30  drops  H2SO4,  evaporate  down  until  copious  * 

fumes  of  SO3  are  given  off,  dissolve  in  water  with  a  little  HC1  if 
necessary,  transfer  to  a  small  platinum  dish,  dilute  to  100  c.c.,  heat 
to  boiling,  and  add  excess  of  ammonia.  Boil  for  a  few  minutes, 
and  filter  from  the  A12OS  etc.  into  another  platinum  dish.  Evapo- 
rate the  filtrate  to  dryness,  and  heat  until  the  chloride  and  sulphate 
of  ammonium  are  volatilized.  Treat  the  residue  with  a  little  water, 
heat  to  boiling,  and  add  enough  oxalate  of  ammonium  to  precipi- 
tate all  the  calcium,  filter  into  another  platinum  dish,  evaporate  to 
dryness,  and  heat  to  dull  redness.  Treat  the  residue  with  a  little 
water,  heat  the  filtrate  to  boiling,  add  enough  acetate  of  barium  to 
precipitate  all  the  H2SO4,  boil,  and  filter.  Evaporate  the  filtrate  to 
dryness  and  heat  to  redness  to  decompose  the  acetates.  Treat  the 


S  " 

(Tf  -NTTVERSIT  T 


256 


ANALYSIS   OF  IRON  ORES. 


KC1  + 
NaCl. 


K2PtCl6. 

K20. 

KC1. 

Nad. 

Na2O. 


Treatment 
of  the  por- 
tion of  the 
ore  soluble 
in  HC1. 


Decompo- 
sition of 
insoluble 
matter  by 
CaC03 
and 
HN4C1. 


residue  with  water,  filter  from  the  insoluble  carbonate  of  barium, 
add  a  few  drops  of  barium  hydrate,  and  evaporate  again  to  dry- 
ness.  Dissolve  in  a  few  c.c.  of  water,  and  filter  into  a  weighed 
crucible. 

Evaporate  very  low,  and,  if  nothing  separates  out,  add  a  few 
drops  of  HC1,  evaporate  to  dryness,  heat  to  very  dull  redness,  cool, 
and  weigh  as  KC1  +  NaCl.  To  the  residue  in  the  crucible  add  a 
little  water,  in  which  the  residue  should  dissolve  perfectly,  and  a 
solution  of  platinic  chloride.  Evaporate  down  in  the  water-bath 
until  the  mass  in  the  crucible  solidifies  upon  cooling,  add  a  little 
water  to  dissolve  the  excess  of  platinic  chloride,  and  then  an  equal 
volume  of  alcohol.  Filter  on  a  Gooch  crucible,  wash  with  alco- 
hol until  the  filtrate  runs  through  perfectly  colorless,  dry  at  120° 
C,  and  weigh  as  K2PtCl6.  This  weight  multiplied  by  .19395  gives 
the  weight  of  K2O.  Then  multiply  the  weight  of  K2PtCl6  by 
.30696,  which  gives  the  weight  of  KCL  Subtract  this  from  the 
weight  of  KC1  -j-  NaCl  previously  obtained,  and  the  difference  is 
the  weight  of  NaCl,  which  multiplied  by  .53077  gives  the  weight 
of  Na2O. 

To  the  filtrate  from  the  insoluble  silicious  matter  add  an  excess 
of  ammonia,  rub  a  little  grease  or  parafifine  on  the  edge  of  the 
dish,  and  evaporate  the  mass  to  dryness.  This  will  render  the 
Fe2O3  very  compact  and  granular.  Dilute  with  hot  water,  add  a 
few  drops  of  ammonia,  filter  into  another  platinum  dish,  add  a 
few  drops  of  H2SO4,  evaporate  to  dryness,  and  ignite  to  drive  off 
all  the  ammonia  salts.  Then  proceed  exactly  as  directed  for  the 
determination  of  the  alkalies  in  the  insoluble  silicious  matter. 
The  alkalies  in  the  insoluble  silicious  matter  may  also  be  deter- 
mined by  J.  Lawrence  Smith's  method  of  fusion  with  carbonate  of 
calcium  and  chloride  of  ammonium,  as  directed  farther  on. 

The  chloride  of  ammonium,  which  is  so  troublesome  in  alkali 
determinations,  may  be  decomposed  *  very  easily  by  evaporating 


*  J.  L.  Smith,  Am.  Jour.  Sci.  and  Art,  1871,  $d  Ser.,  vol.  i.  (whole  No.  ci.)  p.  269. 


DETERMINATION  OF  CARBONIC  ACID.  257 


the  solution  down  very  low,  transferring  to  a  tall  beaker  or  flask, 
and  heating  with  a  large  excess  of  HNO3,  —  3  or  4  c.c.  HNO3  to  NH4ciby 
every  gramme  of  NH4C1  supposed  to  be  present.  The  decom- 
position  takes  place  at  a  temperature  below  the  boiling-point  of 
water,  and  when  the  action  seems  to  be  over,  transfer  to  a  porce- 
lain dish,  and  evaporate  to  dryness  after  adding  a  few  drops  of 
H2SO4.  Dissolve  in  water,  filter  into  a  platinum  dish,  and  pro- 
ceed with  the  analysis  in  the  usual  way. 


DETERMINATION    OF    CARBONIC    ACID. 

Weigh  3  grammes  of  finely-ground  ore  into  the  flask  A,  Description 
-  93 »  anc*  connect  the  apparatus  in  the  manner  shown  in  the  apparatus, 
sketch.  L,  L  are  tubulated  bottles  for  forcing  a  current  of  air 
through  the  apparatus.  The  air  is  deprived  of  any  CO2  which  it 
may  contain  by  passing  through  the  tube  M,  which  is  filled  with 
lumps  of  caustic  potassa.  M  is  connected  with  the  bulb-tube  B  by 
the  tube  N,  a  piece  of  gum  tubing  over  the  slightly  tapering  end 
making  an  air-tight  connection  with  B.  O  is  a  condenser  and 
serves  to  condense  the  steam  and  acid  from  the  flask  A.  P 
contains  anhydrous  CuSO4,  and  Q  contains  chloride  of  calcium. 
The  potash-bulb  and  the  drying-tube  R  form  the  absorption 
apparatus,  and  S  is  a  safety-tube  filled  with  CaCl2  to  prevent  R 
from  absorbing  moisture  from  the  atmosphere.  Weigh  the  ab- 
sorption apparatus  with  the  precautions  mentioned  on  page  146, 
and  connect  the  apparatus.  Close  the  stopcock  C,  and  draw  a  Details 
little  air  through  the  apparatus  by  means  of  a  piece  of  gum  ofthe 
tubing  attached  to  the  end  of  S.  Allow  the  tension  of  the  air 
to  draw  the  solution  up  into  the  rear  limb  of  the  potash-bulb, 
and  if  it  remains  there  for  a  reasonable  length  of  time  the  con- 
nections may  be  considered  tight.  Pour  into  the  bulb  B  10 
c.c.  HC1  diluted  with  about  65  c.c.  water,  connect  the  tube 

17 


258 


ANAL  YSIS   OF  IRON  ORES. 


DETERMINATION  OF  COMBINED    WATER.  2-g 

N,  and  by  means  of  the  stopcock  C  allow  the  acid  to  flow  slowly 
into  the  flask  A.  When  the  acid  has  all  run  in,  by  opening 
slightly  the  stopcock  in  L,  start  a  slow  current  of  air  through  the 
apparatus.  Warm  the  flask  A,  gradually  increasing  the  heat  until 
the  solution  boils,  and  continue  the  application  of  heat  until  a 
considerable  amount  of  water  has  condensed  in  O.  Allow  it  to 
cool  while  the  current  of  air  is  continued,  detach,  and  weigh  the 
absorption  apparatus.  The  increase  of  weight  is  the  weight  of 
CO,.  co2. 


DETERMINATION     OF     COMBINED    WATER     AND 
CARBON    IN    CARBONACEOUS    MATTER. 

The  ores  are  very  rare  indeed  in  which  the  combined  water 
can  be  accurately  determined  by  simply  heating  them  in  a  cruci- 
ble and  calling  the  loss  by  ignition  "Water  of  Composition."  LOSS  by 

ignition, 

Nor  is  the  method  of  absorbing  the  moisture,  driven  off  by  heat, 
in  a  drying-tube  much  more  reliable.  The  presence  of  pyrites,  of 
organic  matter,  of  graphite,  and  of  binoxide  of  manganese  serves  to 
complicate  the  problem.  The  water  of  composition  may  indeed  Combustion 

with  chro- 

be  determined  with  great  accuracy  by  heating  the  ore  in  a  tube     mate  of 


with  chromate  of  lead  and  bichromate  of  potassium,  exactly  as  de- 
scribed  for  the  determination  of  carbon  in  iron  and  steel  by  direct 
combustion,  page  132^  seq.  The  increase  of  weight  of  the  U  tube 
which  is  attached  to  the  end  of  the  combustion-tube  (and  which 
should  be  filled  in  this  case  with  granulated  dried  CaCl2)  is  the 
weight  of  "Combined  Water"  in  the  amount  of  ore  used.  By  Combined 
attaching  the  absorption  apparatus  we  likewise  obtain  the  total 
CO2  in  the  ore,  or  that  existing  as  CO2  in  the  carbonates,  and 
that  due  to  the  oxidation  of  any  carbon  existing  as  carbonaceous 
or  organic  matter  or  as  graphite.  By  subtracting  from  the  weight 
of  CO2  thus  obtained  the  amount  of  CO2  existing  as  carbonate 
and  determined  by  the  method  last  given,  and  multiplying  the 


26O 


ANALYSIS   OF  IRON  ORES. 


Details 
of  the 
method. 


difference  by  .27273,  we  get  the  weight  of  "  Carbon  in  carbona- 
When  it  is  necessary  to  make  a  large  number  of 
these  determinations,  the  matter  is  very  much  simplified  by  using 
the  apparatus  shown  in  Figs.  95  and  96.*  Fig.  95  shows  the 
details  of  a  form  of  tubulated  platinum  crucible  suggested  by  Dr. 
Gooch,  which  consists  of  the  crucible  with  a  flange  at  d  into  which 
fits  the  cap.  This  cap  consists  of  a  conical  cover,  H,  drawn  up 


FIG.  95. 


Carbon  in 
carbona- 
ceous mat-  ceous  matter." 


Tubulated 
crucible. 


5 

-1  INCHES 


vertically  into  the  tube  I.  The  horizontal  tube  J  is  burned  into  I, 
and  through  the  centre  of  I  passes  the  small  tube  K,  which, 
expanding  at  a,  is  burned  into  I  at  this  point,  sealing  it  securely. 
The  tubes  N  and  M  of  glass  are  fused  to  K  and  J  at  C  and  b 
respectively.  In  analyzing  ores  containing  much  water  or  car- 
bonic acid,  use  I  gramme ;  for  others,  use  3  grammes.  Weigh  the 
finely-ground  ore  into  a  small  agate  mortar,  and  mix  it  thoroughly 
with  7  to  10  grammes  of  previously  fused  bichromate  of  potas- 
sium, transfer  it  to  the  crucible  A,  Fig.  96,  and  place  it  in  an  air-bath 


*  Tenth  Census  of  the  U.  S.,  Mining  Industries,  vol.  xv.  p.  519. 


DETERMINATION  OF  COMBINED    WATER. 

heated  to  100°  C.  to  drive  off  any  hygroscopic  moisture.  When 
perfectly  dry,  attach  the  cap  B  to  the  crucible,  and  stand  the  latter 
in  the  triangle  C.  Close  the  end  N  .with  a  piece  of  rubber  tubing 
in  the  other  end  of  which  is  fitted  a  piece  of  glass  rod.  Attach 
the  weighed  drying-tube  D,  filled  with  CaCl2,  to  the  horizontal 
tube  from  B,  by  means  of  a  thoroughly  dried  velvet  cork.  Attach 
the  absorption  apparatus  E  and  F  and  the  safety-tube  G.  Fill  the 
outside  of  the  flange  d  with  small  pieces  of  fused  tungstate  of 

FIG    96. 


26l 


sodium,  and,  with  a  blow-pipe  flame,  melt  them,  having  previously 
immersed  the  lower  end  of  A  in  a  small  beaker  of  ice-water.  The 
expansion  of  the  air  in  the  crucible  by  the  heat  applied  to  melt  the 
tungstate  of  sodium  will  force  some  bubbles  through  the  potash- 
bulb  E,  and  the  subsequent  cooling  of  the  air  in  A  will  cause  the 
liquid  in  E  to  flow  back  into  the  rear  bulb.  If  the  difference  of 
level  thus  produced  be  maintained  for  some  minutes,  the  connec- 
tions may  be  considered  tight.  Connect  N  with  the  bottles  L,  as 
shown  in  the  sketch,  and  start  a  current  of  air  through  the  appara- 
tus. The  air  is  purified  from  CO2  and  moisture  by  passing  through 
Q,  which  is  filled  with  fused  caustic  potassa.  Now,  by  means  of  the 


262  ANALYSIS   OF  IRON  ORES. 

blast-lamp  P,  heat  the  crucible  just  above  the  top  of  the  mixture, 
and  gradually  carry  the  heat  downward,  increasing  it  at  the  same 
time.  This  will  keep  the  mixture  from  frothing  and  choking  the 
tube.  Finally,  heat  the  bottom  of  the  crucible  by  the  burner  O, 
and  continue  the  application  of  the  heat  for  ten  minutes.  During 
the  whole  of  the  operation  the  air  passes  through  N  and  K  into 
the  crucible  and  out  through  J  and  M  (Fig.  95)  into  D  (Fig.  96), 
and  so  through  the  apparatus.  The  moisture  from  the  ore  should 
not  be  allowed  to  condense  in  the  wide  part  of  D  at  ft  but  should 
be  driven  forward  into  the  CaCl2  by  warming  the  tube  at  f  with 
the  flame  from  an  alcohol  lamp.  Allow  the  apparatus  to  cool 
while  the  current  of  air  is  continued,  then  detach,  and  weigh  the 
tube  D  and  the  absorption  apparatus,  and  calculate  the  results,  as 
directed  on  page  259.  When  detached  from  the  apparatus,  the 
wide  end  of  the  tube  D  may  be  closed  by  a  short  cork,  covered 
with  tin-foil  to  prevent  the  absorption  of  moisture  from  the  atmos- 
cieaningthe  phere.  To  clean  the  crucible,  remove  it  from  the  stand,  and,  hold- 

crucible.         ...  .  r         i  •  • 

ing  it  in  a  piece  ot  asbestos  board  in  an  inclined  position,  melt  the 
tungstate  of  sodium  in  the  flange  d  with  a  blow-pipe  flame  and 
detach  the  cap.  Dissolve  out  the  bichromate  by  placing  the  cruci- 
ble in  a  dish  of  hot  water,  clean  out  the  ore,  dissolve  any  adhering 
oxide  in  HC1,  wash  the  crucible  and  cap  with  hot  water,  dry  them, 
and  they  will  be  ready  for  another  determination. 


DETERMINATION    OF    CHROMIUM. 

The  small  amount  of  chromium  which  is  found  in  some  iron 
ores  is  generally  converted  into  chromate  of  sodium  very  readily 
by  fusion  with  Na2CO3  and  KNO3.  Fuse  I  or  2  grammes  of  the 
finely-ground  ore  with  10  times  its  weight  of  Na2CO3  and  a  little 
KNO3.  Treat  the  fused  mass  with  water  and  wash  it  out  into 
a  small  beaker.  If  the  solution  is  colored  by  manganese,  add  a 


DETERMINATION  OF  CHROMIUM.  263 

little  alcohol,  which  will  precipitate  the  manganese,  leaving  the  indication 

solution,  if  chromium  is  present,  slightly  yellow.     If  the  solution  presence 
is  colorless  it  may  be  considered  proof  of  the  absence  of  chro- 


mium. Otherwise  filter,  wash  the  insoluble  matter  on  the  filter, 
dry  it,  grind  it  with  ten  times  its  weight  of  Na2CO3  and  a  little 
KNO3,  fuse  it,  treat  with  water  as  before,  filter,  and  add  this  filtrate 
to  the  other.  Acidulate  the  combined  filtrates  with  HC1,  evaporate 
to  dryness  to  render  the  silica  insoluble,  and  reduce  the  chromic 
acid  to  Cr2O3.  Treat  the  mass  with  HC1,  dilute,  filter,  and  precipi- 
tate the  Cr2O3  -+-  A12O3  by  ammonia.  Boil  for  some  minutes,  filter, 
wash  well  with  hot  water,  dry,  and  ignite  the  precipitate.  Fuse 
with  as  little  Na2CO3  and  KNO3  as  possible,  treat  with  water,  and 
wash  the  solution  into  a  platinum  dish.  Evaporate  the  solution  separation 
until  it  is  very  concentrated,  adding  from  time  to  time  crystals  of  Ai2o8. 
nitrate  of  ammonium  to  change  all  the  carbonated  and  caustic 
alkali  to  nitrate.  At  each  addition  of  the  nitrate  of  ammonium 
the  solution  effervesces,  and  carbonate  of  ammonium  is  given  off. 
When  the  solution  is  nearly  syrupy,  the  addition  of  nitrate  of  am- 
monium no  longer  causes  an  effervescence,  and  the  solution  smells 
faintly  of  ammonia,  add  a  few  drops  of  NH4HO,  and  filter.  By 
this  operation  all  the  alumina,  phosphate  of  aluminium,  oxide  of 
manganese,  etc.,  are  precipitated,  and  there  remain  in  solution 
only  the  alkalies  and  the  chromate  of  the  alkalies.  To  the  fil- 
trate add  an  excess  of  sulphurous  acid  in  water,  which  instantly 
changes  the  color  of  the  solution  from  yellow  to  green.  Boil  well, 
add  an  excess  of  ammonia,  boil  for  a  few  minutes,  filter  on  an 
ashless  filter,  wash  well  with  hot  water,  dry,  ignite,  and  weigh 
as  Cr2O3.  Crso8. 

Chrome  iron  ore  is  best  decomposed  by  Genth's  *  method  of   chrome 
fusing  .5  gramme  of  very  finely  ground  ore  with  bisulphate  of 
potassium,  raising  the  heat  very  gradually  until  finally  the  highest 
temperature  of  the  lamp  is  attained,  allowing  it  to  cool,  adding 

*  Chem.  News,  vol.  vi.  p.  31. 


264  ANALYSIS   OF  IRON  ORES. 

5  grammes  Na2CO3  and  I  gramme  KNO3,  and  heating  gradually 
to  complete  fusion,  allowing  it  to  remain  so  for  fifteen  or  twenty 
minutes,  treating  with  water,  and  proceeding  as  directed  above. 


DETERMINATION   OF   TUNGSTEN. 

Digest  from  i  to  10  grammes  of  the  ore  in  HC1,  adding  HNO3 
from  time  to  time.  When  the  ore  appears  to  be  perfectly  decom- 
posed, evaporate  to  dryness  on  the  water-bath  (a  higher  tem- 
perature is  not  admissible,  as  it  may  render  the  WO3  insoluble 
in  NH4HO),  redissolve  in  HC1,  and  evaporate  down  again.  Re- 
dissolve  in  HC1,  dilute,  filter,  wash  with  acidulated  water,  and 
finally  with  alcohol.  Treat  on  the  filter  with  ammonia,  allowing 
the  filtrate  to  run  into  a  platinum  dish,  evaporate  to  small  bulk, 
add  excess  of  ammonia,  filter,  if  necessary,  into  a  platinum  cru- 
cible, evaporate  carefully  to  dryness,  heat  gently  to  drive  ofT  the 
ammonia,  and  ignite.  Weigh  as  WO3. 


DETERMINATION    OF   VANADIUM. 

Fuse  5  grammes  of  the  very  finely  ground  ore  with  30 
grammes  of  Na2CO3  and  from  I  to  5  grammes  of  NaNO3,  and 
proceed  exactly  as  in  the  determination  of  vanadium  in  pig-iron, 
page  199.  A  second  fusion  of  the  residue  from  the  aqueous 
solution  of  the  first  fusion  is  hardly  ever  necessary. 


DETERMINATION  OF  SPECIFIC   GRAVITY. 


265 


FIG.  97. 


DETERMINATION    OF    SPECIFIC   GRAVITY. 

The  specific  gravity  of  iron  ores  is  determined  with  much 
greater  accuracy  by  using  the  powdered  material  than  by  using 
lumps  of  the  ore.  The  little  flask 
shown  in  Fig.  97  was  designed  for  this 
purpose  by  the  late  Mr.  James  Ho- 
garth,* and  its  use  avoids  two  diffi- 
culties experienced  in  the  use  of  the 
ordinary  specific  gravity  bottle, — the 
expansion  and  overflow  consequent 
upon  transferring  the  flask  at  60°  F. 
to  the  higher  temperature  of  the  bal- 
ance-case, and  the  necessity  for  wait- 
ing until  the  finely-divided  particles 
of  the  ore  shall  have  settled  before 
inserting  the  stopper.  These  difficul- 
ties were  overcome  by  melting  a  capil- 
lary tubulus  to  the  lower  part  of  the 
neck  of  the  flask,  and  by  grinding  in 

a  stopper  having  a  small  bulb  above  the  capillary,  to  allow  for 
expansion.  The  operation  is  conducted  as  follows :  Transfer  a 
weighed  amount  of  the  ore  to  the  flask,  add  enough  water  to 
cover  it,  and  heat  it  almost  to  the  boiling-point  by  placing  it  in 
the  water-bath.  Place  the  flask  under  a  bell-jar  connected  with 
an  aspirator  or  air-pump,  and  expel  all  the  air  by  allowing  it  to 
boil  for  some  time  at  a  reduced  pressure.  Remove  it  from  the 
bell-jar,  fill  it  up  to  the  tubulus  with  cold  water,  insert  the  stopper, 
and  cool  the  flask  and  its  contents  to  about  60°  F.  By  suction 
on  the  stopper  draw  water  through  the  tubulus  until  it  is  slightly 
above  the  capillary  of  the  stopper,  at  which  point  a  mark  is 
scratched.  When  the  flask  and  its  contents  are  exactly  at  60°  F., 


Hogarth's 
flask. 


Its  advan- 
tages. 


*  Tenth  Census  of  the  U.  S.,  vol.  xv.  p.  522. 


ANALYSIS   OF  IRON  ORES. 

adjust  the  volume  exactly  to  the  mark  on  the  capillary  by  touch- 
ing a  piece  of  blotting-paper  to  the  end  of  the  tubulus  or  by  draw- 
ing a  little  water  in  through  it.  Dry  the  flask,  allow  it  to  acquire 
the  temperature  of  the  balance-case,  and  weigh  it.  Now,  if  W  is 
the  weight  of  ore  taken,  W  the  weight  of  the  ore  and  water  at 
60°  F.,  and  K  the  weight  of  the  flask  and  its  contents  to  the 
mark  of  water  at  60°  F.,  then 

W 
Sp-gr'  =  W+K-W 

To  obtain  I£,  fill  the  flask  with  boiled  water,  and  treat  it  exactly 
as  described  above. 


METHODS  FOR  THE  ANALYSIS 


OF 


LIMESTONE. 


DETERMINATION  OF  INSOLUBLE  SILICIOUS 
MATTER,  ALUMINA  AND  OXIDE  OF  IRON, 
CARBONATE  OF  CALCIUM,  AND  CARBONATE 
OF  MAGNESIUM. 

WEIGH  I  gramme  of  the  powdered  limestone,  previously  dried 
at  1 00°  C.,  into  a  No.   I  beaker,  cover  with  a  watch-glass,  and 
pour  in  5  c.c.  of  HC1  diluted  with  25  c.c.  of  water  and  a  little 
bromine-water.      Digest   on   the   sand-bath    until    all   the   action 
ceases,  wash  the  watch-glass  with  a  fine  jet  of  water,  and  evap- 
orate to  dryness.     Redissolve  in  10  c.c.  HC1  diluted  with  50  c.c. 
water,  filter  on  a  small  ashless  filter,  wash  well  with  hot  water, 
dry,  ignite,  and  weigh  as  Insoluble  Silicious  Matter.     Heat  the  fil-  insoluble 
trate  to  boiling,  add  a  slight  excess  of  ammonia,  boii  for  a  few     Matter.8 
minutes,  filter,  wash  once  or  twice.     Dissolve  the  precipitate  on  Resolution 
the  filter  in  a  little  dilute  HC1,  allowing  the  solution  to  run  into     ^^ 
the  beaker  in  which  the  precipitation  was  made,  wash  well  with     a'piAtft" 

Of  AloOs 

water,  dilute,  boil,  and   reprecipitate  by  ammonia.      Filter  on  a     andFe2o3. 
small  ashless  filter,  allow  this  filtrate  to  run  into  the  beaker  con- 
taining the  first  one,  wash  well  with  hot  water,  dry,  ignite,  and  Ai2o3and 
weigh  as  A12O3  and  Fe2O3.     Heat  the  united  filtrates  to  boiling,  Quantity  of 
add  enough  oxalate  of  ammonium  to  convert  all  the  calcium  and     ammo. 
magnesium  into  oxalates.*     Allow  the  precipitate  of  oxalate  of 


cessary. 


25  c.c.  of  the  saturated  solution  is  about  the  proper  quantity. 

267 


268 


ANAL  YSIS   OF  LIMESTONE. 


CaO. 


CaC03 

Quantity  of 
microcos- 
mic  salt 
required. 


MgO  and 
MgC03. 

Other  sub- 
stances 
found  in 
lime- 
stones. 


calcium  to  settle  for  fifteen  or  twenty  minutes,  filter  on  an  ash- 
less  filter,  wash  with  hot  water,  dry,  ignite  for  some  time  over  a 
Bunsen  burner,  and  finally  for  fifteen  minutes  at  the  highest  tem- 
perature of  a  blast-lamp.  Cool  in  a  desiccator,  weigh  quickly, 
ignite  again  over  the  blast-lamp  for  five  minutes,  cool,  and  weigh 
again.  If  this  weight  is  the  same,  or  nearly  the  same,  as  the 
previous  one,  call  the  amount  CaO.  If  the  second  weight  is 
much  less  than  the  first,  ignite,  and  weigh  again  until  the  weight 
is  constant.  The  weight  of  CaO  multiplied  by  1.78459  gives  the 
weight  of  CaCO3.  Add  to  the  filtrate  from  the  oxalate  of  cal- 
cium 30  c.c.  of  a  saturated  solution  of  microcosmic  salt  (phos- 
phate of  sodium  and  ammonium),  acidulate  with  HC1,  and  evap- 
orate the  solution  to  about  300  c.c.  If  during  the  evaporation 
any  precipitate  should  separate  out,  redissolve  it  in  HC1.  Cool 
the  evaporated  solution  in  ice-water,  and  add  ammonia  drop  by 
drop,  stirring  the  solution,  but  being  careful  to  avoid  rubbing 
the  sides  of  the  beaker  with  the  rod,  as  the  precipitate  of 
Mg2(NH4)2P2O8  -J-  I2H2O  is  liable  to  adhere  with  great  tenacity 
to  those  points  or  lines  where  the  rod  has  touched  the  sides  or 
bottom  of  the  beaker.  Continue  the  addition  of  ammonia  until 
the  solution  is  decidedly  alkaline,  and  then  add  an  amount  equal  to 
one-fourth  of  the  neutralized  solution.  After  the  precipitate  has 
begun  to  form,  stir  vigorously  several  times,  allow  to  stand  over- 
night, filter  on  an  ashless  filter,  rub  off  with  a  "  policeman"  any 
of  the  precipitate  that  may  adhere  to  the  beaker,  wash  with  a 
mixture  of  I  part  ammonia  and  2  parts  water,  containing  100 
grammes  of  nitrate  of  ammonium  to  the  litre,  dry,  ignite  with 
great  care,  as  directed  on  page  85,  cool,  and  weigh  as  Mg2P2O7, 
which  multiplied  by  .36212  gives  the  weight  of  MgO,  and  multi- 
plied by  .75760  gives  the  weight  of  MgCO3. 

Limestones,  besides  the  ordinary  constituents  mentioned 
above,  may  contain  small  amounts  of  phosphoric  acid,  sulphur 
as  sulphate  or  as  pyrites,  titanic  acid,  organic  matter,  combined 
water,  alkalies,  manganese,  fluorine,  and  in  rare  instances  nearly 


DETERMINATION  OF  PHOSPHORIC  ACID.  269 

all  the  metals  found  in  iron  ores.  For  most  of  these  the  methods 
described  in  the  analysis  of  iron  ores  may  be  employed.  Very 
often  the  amounts  of  silica  and  alumina  are  required  in  calculating 
mixtures  for  the  blast-furnace,  and,  as  the  matter  insoluble  in  HC1 
consists  usually  of  silicates  of  alumina,  lime,  and  magnesia,  it  Determina- 
would  be  necessary  in  accurate  work  to  decompose  the  Insoluble  Sio2. 
Silicious  Matter  by  fusion  with  carbonate  of  sodium  and  to  make 
a  separate  analysis  of  it,  as  described  on  page  239.  It  is,  indeed, 
much  better  to  make  the  analysis  in  this  way  than  to  add  the 
filtrate  from  the  silica  to  the  main  solution,  for  the  oxalate  of 
calcium  is  sure  to  carry  down  some  of  the  sodium  salts  with  it 
and  thus  very  materially  complicate  the  analysis. 

After  weighing  the  A12O3  and  Fe2O3  from  the  Insoluble  Silicious 
Matter  and  that  from  the  portion  soluble  in  dilute  HC1  to  deter- 
mine the  Fe2O3,  fuse  the  two  precipitates  with  a  little  carbonate 
of  sodium,  dissolve  in  water,  acidulate  with  HC1  in  a  beaker,  add 
a  few  small  crystals  of  citric  acid  to  the  clear  solution,  then  excess 
of  ammonia  and  sulphide  of  ammonium.  Allow  the  precipitate  of 
sulphide  of  iron  to  settle,  filter,  wash  slightly,  dissolve  in  HC1,  add 
a  little  bromine-water,  boil  the  solution,  precipitate  by  ammonia, 
filter,  wash,  ignite,  and  weight  as  Fe2O3.  The  weight  of  Fe2O3  Fe2o3. 
subtracted  from  the  weight  of  the  total  A12O3  -f  Fe2O3  gives,  of  Ai2o3. 
course,  the  weight  of  A12O3. 

The  CaO  and  MgO  in  the  Insoluble  Silicious  Matter  should  not  Cao  and 

MgOin 

be  calculated  as  carbonates,  but  should  be  considered  as  existing     insoluble 

r+    r\  i    T\T     r\  Silicious 

as  CaO  and  MgO.  Matter. 

To  determine  phosphoric  acid  in  limestones,  treat  20  grammes   Determina- 
with  dilute  HC1,  filter  from  the  Insoluble  Silicious  Matter,  to  the     p°o6° 
filtrate  add  a  few  drops  of  ferric  chloride  solution,  then  ammonia 
until  the  solution  is  alkaline  to  litmus-paper,*  and  acetic  acid  to 
decided  acid  reaction.     Boil  for  a  few  minutes,  filter,  wash  once 


*  If  the  precipitate  is  not  decidedly  red  in  color,  acidulate  with  HC1  and  add 
more  ferric  chloride  solution. 


2/0 


ANALYSIS   OF  LIMESTONE. 


Treatment 
of  In- 
soluble 
Silicious 
Matter. 


Treatment 
of  In- 
soluble 
Silicious 
Matter 
by  direct 
fusion. 


Sulphur  in 
limestone. 


with  hot  water,  dissolve  in  HC1  on  the  filter,  allowing  the  solution 
to  run  into  the  beaker  in  which  the  precipitation  was  made,  add 
the  solution  from  the  treatment  of  the  Insoluble  Silicious  Matter 
mentioned  below,  dilute,  and  reprecipitate  exactly  as  before  with 
ammonia  and  acetic  acid.  Dissolve  this  precipitate  on  the  filter 
in  dilute  HC1,  allowing  the  solution  to  run  into  a  No.  I  beaker, 
wash  the  filter  with  hot  water,  evaporate  the  solution  down  almost 
to  dryness,  and  precipitate  the  P2O5  as  directed  on  page  85. 

Ignite  the  Insoluble  Silicious  Matter,  treat  it  with  HF1  and  a 
few  drops  of  H2SO4,  evaporate  until  fumes  of  SO3  are  given  off, 
fuse  with  Na2CO3,  digest  in  water,  filter,  acidulate  the  solution 
with  HC1,  and  add  it  to  the  solution  of  the  first  precipitate  in  the 
soluble  portion  as  mentioned  above. 

Instead  of  treating  the  Insoluble  Silicious  Matter  with  HF1  and 
H2SO4,  it  may  be  fused  at  once  with  Na2CO3,  the  fused  mass 
treated  with  water,  filtered,  the  filtrate  acidulated,  evaporated  to 
dryness,  redissolved  in  water  slightly  acidulated  with  HC1,  filtered, 
and  the  filtrate  added  to  the  solution  of  the  first  precipitate  by 
ammonia  and  acetic  acid  as  above. 

To  determine  sulphur  in  limestone,  fuse  I  gramme  with 
Na2CO3  and  KNO3  exactly  as  in  the  determination  of  sulphur  in 
iron  ores,  page  226  et  seq. 

To  determine  sulphates,  proceed  as  in  the  analysis  of  iron  ores 
for  these  substances,  page  228  et  seq. 


METHODS   FOR   THE   ANALYSIS 

OF 

CLAY. 


CLAY  is  essentially  silica,  mixed  with  silicates  of  aluminium, 

.   .  tion  of 

calcium,  magnesium,  potassium,  and  sodium.  These  silicates  are  ciay. 
hydrated,  so  that  clay  usually  contains  from  6  to  12  per  cent,  of 
water  of  composition.  Besides  these  usual  constituents,  clay  may 
contain  oxide  of  iron,  titanic  acid,  pyrites,  organic  matter,  phos- 
phoric acid,  and  occasionally  some  of  the  rarer  elements,  such 
as  vanadium. 

Clay  being  practically  unacted  on  by  HC1,  it  is  necessary  to  Method  of 
proceed  as  follows :  Fuse  I  gramme  of  the  finely-ground  clay 
dried  at  100°  C.  with  10  grammes  of  Na2CO3  and  a  very  little 
NaNO3.  Run  the  fused  mass  well  up  on  the  sides  of  the  crucible, 
allow  it  to  cool,  and  treat  it  with  hot  water  until  thoroughly  disin- 
tegrated, transferring  the  liquid  from  time  to  time  to  a  platinum 
dish.  Treat  the  crucible  with  HC1,  add  this  to  the  liquid  in  the 
dish,  acidulate  with  HC1,  and  evaporate  to  dryness  in  the  air-bath. 
Treat  the  mass  with  water  and  a  little  HC1,  evaporate  again  to 
dryness,  and  treat  with  15  c.c.  HC1  and  45  c.c.  water.  Allow  it 
to  stand  in  a  warm  place  for  fifteen  or  twenty  minutes,  add  50 
c.c.  water,  and  filter  on  an  ashless  filter.  Wash  thoroughly  with 
hot  water  acidulated  with  a  few  drops  of  HC1,  dry,  ignite,  heat  for 
three  or  four  minutes  over  the  blast-lamp,  and  weigh.  Treat  the 
precipitate  with  HF1  and  a  few  drops  of  H2SO4,  evaporate  to  dry- 
ness,  ignite,  and  weigh.  The  difference  between  the  two  weights  is 

271 


2/2 
SiO2. 


A1203  + 
Fe203. 


A1203. 


CaO  and 
MgO. 

Determina- 
tion of 
alkalies. 


ANALYSIS   OF  CLAY. 

SiO2.  If  any  appreciable  residue  remains  in  the  crucible,  treat  it 
with  a  little  HC1,  and  wash  it  out  into  the  filtrate  from  the  silica. 
Transfer  the  filtrate  from  the  silica  to  a  large  platinum  dish,  heat 
it  to  boiling,  add  an  excess  of  ammonia,  boil  until  the  smell  of 
NH3  is  quite  faint,  filter  on  an  ashless  filter,  and  wash  several 
times  with  hot  water.  Stand  the  filtrate  and  washings  aside,  and 
treat  the  precipitate  on  the  filter  with  a  mixture  of  15  c.c.  HC1 
and  15  c.c.  water,  cold.  Allow  the  solution  to  run  into  a  small 
clean  beaker,  replace  this  by  the  platinum  dish  in  which  the  pre- 
cipitation was  made,  pour  the  solution  on  the  filter  again,  and 
repeat  this  operation  until  the  precipitate  has  completely  dissolved. 
Wash,  out  the  beaker  into  the  filter,  wash  the  latter  thoroughly 
with  cold  water,  dry,  and  preserve  it.  Reprecipitate  by  ammonia, 
as  above  directed,  filter  on  an  ashless  filter,  wipe  out  the  dish  with 
small  pieces  of  filter-paper,  add  these  to  the  precipitate,  and  wash 
thoroughly  with  hot  water.  Dry,  ignite  the  precipitate  and  filter, 
and  the  filter  from  the  first  precipitation,  heat  for  a  few  minutes 
over  the  blast-lamp,  cool,  and  weigh  as  A12O3  and  Fe2O3.  Fuse 
the  ignited  precipitate  with  Na2CO3,  treat  the  fused  mass  with 
water,  wash  it  out  into  a  small  beaker,  allow  the  residue  to 
settle,  decant  off  the  clear,  supernatant  fluid,  treat  the  residue  with 
HC1,  and  determine  the  iron  volumetrically,  or  add  citric  acid  and 
ammonia,  and  precipitate  the  iron  as  sulphide.  Filter,  wash,  dis- 
solve in  HC1,  oxidize  with  bromine-water,  and  precipitate  the 
Fe2O3  by  ammonia.  Filter,  wash,  dry,  ignite,  and  weigh  as  Fe2O3. 
Subtract  the  weight  of  Fe2O3  from  the  A12O3  -f  Fe2O3  found  above, 
and  the  difference  is  A12O3. 

As  the  amounts  of  calcium  and  magnesium  in  clay  are  very 
small,  the  filtrate  and  washings  from  the  second  precipitation  of 
A12O3  +  Fe2O3  may  be  rejected  and  the  CaO  and  MgO  deter- 
mined in  the  first  filtrate  as  directed  on  page  240. 

To  determine  the  alkalies  in  clay,  treat  2  grammes  of  the  finely- 
ground  material  in  a  platinum  dish  with  4  c.c.  of  strong  H2SO4 
and  40  or  50  c.c.  of  redistilled  HF1.  Stir  it  from  time  to  time 


DETERMINATION  OF   THE  ALKALIES.  273 


with  a  platinum  wire  or  rod,  heating  carefully,  until  the  clay  is 
entirely   decomposed  and  no  more  gritty  substance  can  be  felt     HFiand 

TT    C(") 

under  the  rod.  Evaporate  to  dryness,  and  heat  until  fumes  of 
SO3  are  given  off.  The  entire  operation  should  be  carried  on 
under  a  hood  with  a  good  draft,  as  HF1  is  very  poisonous,  and  the 
evaporation  may  be  safely  conducted  on  the  little  arrangement 
shown  in  Fig.  10,  page  20.  Allow  the  dish  to  cool,  add  about 
50  c.c.  water  and  a  little  HC1,  and  heat  until  the  mass  is  all  dis- 
solved. If  any  of  the  clay  has  escaped  decomposition,  filter  into 
another  platinum  dish,  wash  the  insoluble  matter  on  the  filter, 
dry,  ignite,  and  decompose  it  in  the  crucible  with  HF1  and  H2SO4. 
Dissolve  the  mass  in  the  crucible  after  evaporating  off  the  HF1, 
and  add  the  solution  to  the  main  solution  in  the  dish.  Dilute 
this  solution  to  300  or  400  c.c.  with  hot  water,  heat  to  boiling,  add 
an  excess  of  ammonia,  boil  for  a  few  minutes,  and  filter.  Allow  washing 
the  precipitate  to  drain  well  on  the  filter,  remove  the  filtrate,  which  delated 
should  be  in  a  platinum  dish,  to  a  light,  and  evaporate  it  down. 
Pierce  the  filter  with  a  wire  or  rod,  and  wash  the  precipitate  into 
the  dish  in  which  the  precipitation  was  made  with  a  jet  of  hot 
water.  Dilute  to  300  or  400  c.c.,  add  a  little  ammonia,  heat  to 
boiling,  filter,  and  wash  several  times  with  hot  water.  Add  this 
filtrate  to  the  first  one,  and  evaporate  to  dryness.  Heat  until 
all  the  ammonium  salts  are  volatilized,  and  proceed  exactly  as 
directed  for  the  determination  of  alkalies  in  the  Insoluble  Silicious 
Matter  from  iron  ores,  page  255. 

Instead  of  decomposing  the  clay  by  HF1   and    H2SO4,  the  J.  Lawrence 
method  given  by  J.  Lawrence  Smith  may  be  used  for  determining     method  for 
alkalies.     Weigh  I  gramme  of  the  finely-ground  clay  into  a  por- 
celain or  agate  mortar,  add  an  equal  weight  of  granular  chloride 
of  ammonium,*  and  grind  the  two  together  to  mix  them.     Add 
8  grammes  of  carbonate  of  calcium,f  and  grind  the  entire  mass 
so  as  to  obtain  an  intimate  mixture  of  the  whole.     Transfer  to  a 


See  page  45.  f  See  page  52. 

18 


274 


ANALYSIS   OF  CLAY. 


capacious  platinum  crucible,  cover  with  a  close-fitting  lid,  and 
heat  carefully  to  decompose  the  chloride  of  ammonium,  which  is 
accomplished  in  a  few  minutes.  Heat  gradually  to  redness,  and 
keep  the  bottom  of  the  crucible  at  a  bright  red  for  about  an  hour. 
Allow  the  crucible  to  cool,  and  if  the  mass  is  easily  detached  from 
the  crucible,  transfer  it  to  a  platinum  dish  and  add  about  80  c.c. 
of  water.  Wash  off  the  lid  into  the  crucible  with  water,  heat  this 
to  boiling,  and  wash  the  crucible  out  into  the  dish.  Heat  the 
water  in  the  dish  to  boiling,  and,  when  the  mass  has  completely 
slaked,  filter  into  another  platinum  dish  and  wash  the  mass  on  the 
filter  with  hot  water.  If  the  semi-fused  mass  in  the  crucible  is  not 
easily  detached,  place  the  crucible  on  its  side  in  the  dish,  wash  off 
the  lid  into  the  dish,  add  about  100  c.c.  water,  and  heat  until  the 
mass  disintegrates.  Remove  the  crucible,  wash  it  off  into  the 
dish,  and  filter  as  above  directed.  To  the  filtrate  add  about  i  y2 
grammes  of  pure  carbonate  of  ammonium,  evaporate  on  the 
water-bath,  or  very  carefully  over  a  light,  until  the  volume  of  the 
solution  is  reduced  to  about  40  c.c.,  add  a  little  more  carbonate 
of  ammonium  and  a  few  drops  of  ammonia,  and  filter  on  a  small 
filter.  Evaporate  the  filtrate  carefully  after  adding  a  few  drops 
more  of  carbonate  of  ammonium  to  make  certain  that  all  the  cal- 
cium has  been  precipitated.  If  any  further  precipitate  appears, 
filter  into  a  platinum  crucible  and  evaporate  to  dryness.  Heat 
carefully  to  dull  redness  to  drive  off  any  ammonium  salts,  and 
weigh  the  residue  as  KC1  +  NaCl.  Separate  the  potassium  and 
sodium  as  directed  on  page  256. 

Water  of  Determine  the  water  of  composition  by  igniting  I  gramme  of 

rt°nlp°        the  clay  for  twenty  minutes  at  a  bright  red  heat,  when  the  loss 

of  weight  will    represent   the  water.     In   the   presence   of  much 

organic  matter  or  pyrites  the  method  given  for  the  determination 

of  water  of  composition  in  iron  ores,  page  259,  may  be  used. 

Determina-  To    determine   titanic    acid,  treat    2    grammes    of  the    finely- 

Tio2.         ground   clay  in  a  large   platinum    crucible  with    HF1  and  5   c.c. 

H2SO4.     Evaporate   off  the    HF1,    and    heat    carefully    until    the 


DETERMINATION  OF   TITANIC  ACID. 


275 


greater  part  of  the  H2SO4  is  volatilized.  Allow  the  crucible  to 
cool,  add  10  grammes  of  Na2CO3,  and  fuse  for  thirty  minutes  at 
the  highest  temperature  obtainable  by  a  Bunsen  burner.  Run  the 
fused  mass  well  up  on  the  sides  of  the  crucible,  and  allow  it  to 
cool.  Treat  the  fused  mass  with  water,  transfer  it  to  a  beaker,  and 
filter.  Wash  the  insoluble  matter  slightly  on  the  filter,  dry,  ignite, 
and  fuse  it  again  with  Na2CO3.  Dissolve  in  water  as  before,  and 
filter.  By  this  method  of  treatment  nearly  all  the  alumina  will  be 
dissolved  and  separated  from  the  titanic  acid.  Fuse  the  insoluble 
matter  left  on  the  filter  with  Na2CO3,  and  determine  the  TiO2  as 
directed  on  page  179. 

When  alkalies  are  determined,  the  precipitated  alumina  may  Determina- 

tion of 
be  used  for  the  determination  of  TiO2.     In  this  case  dry  the  pre-     Tio2m 

cipitate  of  A12O3,  etc.,  separate  it  from  the  filter,  ignite  the  two     tion  taken 


filters,  add  the  ash  to  the  dried,  not  ignited,  precipitate  of  A12O3, 

alkalies. 


etc.,  and  fuse  with  Na2CO3  as  above.  n°nof 

1          • 


METHODS  FOR  THE  ANALYSIS 


OF 


SLAGS. 


Composition         BLAST-FURNACE  slags  contain  silica,  alumina,  lime,  magnesia, 

of  blast- 
furnace      and    alkalies    always,    generally    also    ferrous    oxide,    manganous 

oxide,  and  sulphur,  and  occasionally  titanic  acid,  small  amounts 
of  phosphoric  acid,  and  such  metallic  oxides  as  may  exist  in  the 
ores,  fluxes,  or  fuel  used  in  the  furnace.  Sulphur,  which  is  occa- 
sionally present  in  considerable  amounts,  is  considered  to  exist  in 
the  slag  as  sulphide  of  calcium. 

The  method  used  for  the  determination  of  the  principal  in- 
gredients depends  upon  whether  the  slag  is  capable  of  being 
entirely  or  but  partially  decomposed  by  HC1. 

In  the  first  case  weigh  I  gramme  of  the  finely-ground  slag 
into  a  platinum  or  porcelain  dish,  add  20  c.c.  of  water,  and  shake 
the  dish  until  the  material  is  thoroughly  disseminated  through  the 
siags  de-  water.  Add  gradually  30  c.c.  HC1,  with  constant  stirring,  and 
by  HCI.  finally  heat  the  dish  carefully.  The  slag  will  dissolve  completely 
to  a  clear  liquid,  but,  after  heating  for  a  short  time,  will  suddenly 
form  a  solid  jelly.  Evaporate  carefully  to  dryness,  treat  with  a 
few  c.c.  of  dilute  HCI  and  a  little  bromine- water,  evaporate  again 
to  dryness,  and  add  15  c.c.  HCI  and  45  c.c.  water.  Allow  to 
stand  fifteen  or  twenty  minutes  in  a  warm  place,  add  50  c.c.  water, 
filter  on  an  ashless  filter,  wash  thoroughly  with  hot  water,  dry, 
ignite,  and  weigh.  Treat  the  material  in  the  crucible  with  a  little 

water,  add  2  or  3  drops  H2SO4  and  enough  HF1  to  dissolve  it. 
276 


DETERMINATION  OF  SILICA,  ALUMINA,   ETC.  277 

Evaporate   to    dryness,  ignite,  and  weigh.     The   loss    of  weight 

is  SiO2.  Sio2. 

Any  residue  in  the  crucible  after  the  volatilization  of  the  SiO2  Non-voiatiie 
is  to  be  added  to  the  A12O3  -f-  Fe2O3.     Heat  the  filtrate  obtained 
above,  diluted  to  500  c.c.,  to  boiling,  add  a  slight  excess  of  ammo- 
nia, boil  for  a  few  minutes,  filter  on  an  ashless  filter,  and  wash  two 
or  three  times  with  boiling  water.     Stand  the  filtrate  aside,  and 
pour  on  the  precipitate  in  the  filter  a  mixture  of  15  c.c.  HC1  and 
30  c.c.  cold  H2O,  allowing  the  solution  to  run  into  the  dish  in 
which  the  precipitation  was  made.     Alumina  precipitated  in  this 
way  seems  generally  to  dissolve  more  readily  in  cold  than  in  hot  Resolution 
dilute  HC1,  but  it  is  often  necessary  to  break  up  the  precipitate  on     dpitated 
the  filter  with  a  rod,  to  pour  the  acid  solution  back  on  the  filter 
several  times  after  it  has  run  through,  and  sometimes  to  pierce 
the  filter  with  a  rod  or  wire  and  wash  the  precipitate  still  undis- 
solved  into  the  dish.     Wash  the  filter  well  with  water,  dry  it,  and  Preservation 

of  the 

keep  it  to  ignite  with  the  A12O3,  etc.     Heat  the  filtrate  and  wash-     filter. 

ings  to  boiling,  reprecipitate  by  ammonia,  filter  on  an  ashless  filter, 

clean  off  any  adhering  precipitate  from  the  dish  with  filter-paper, 

add  it  to  the  precipitate  on  the  filter,  wash  well  with  hot  water, 

dry,  ignite,  after  adding  the  filter  on  which  the  first  precipitation 

was  filtered,  and  weigh  as  A12O3,  etc.     Add  to  this  the  weight  of 

the  residue  from  the  treatment  of  the  SiO2  by  H2SO4  and  HF1,* 

and  the  sum  is  the  total  A12O3  +  Fe2O3  +  P2O5  +  TiO2.  Ai2o3,etc. 

Evaporate  down  to  about  300  c.c.  the  two  filtrates  obtained  above, 
transfer  to  a  No.  3  beaker,  add  a  few  drops  of  ammonia  and  enough 
sulphide  of  ammonium  to  precipitate  the  manganese.     Filter  off,  and 
determine  the  manganese  as  directed  on  page  234,  in  the  "  Analysis  Mno. 
of  Iron  Ores."     To  the  filtrate  from  the  sulphide  of  manganese  add 
a  slight  excess  of  HC1,  boil  until  all  the  H2S  is  driven  off,  filter 
from  any  precipitated  sulphur,  and  determine  the  CaO  and  MgO  CaOand 
as  directed  on  page  259  et  seq.,  in  the  "  Analysis  of  Limestone." 

*  This  residue  should  be  examined  for  CaO. 


ANALYSIS   OF  SLAGS. 


Determi- 
nation of 
FeO. 


Slags  con- 
taining no 
manga- 
nese. 


Slags  that 
are  not 
entirely 
decom- 
posed 
by  HC1. 


Reprecipi- 
tation  of 
the  CaO. 


Determi- 
nation of 
sulphur 
in  slags. 


Alkalies, 
TiO2,  etc. 


Converter 
slags,  etc. 


To  determine  the  FeO,  fuse  the  ignited  precipitate  of  A12O3, 
etc.,  obtained  above,  with  5  grammes  of  carbonate  of  sodium,  at 
a  very  high  temperature,  for  at  least  thirty  minutes.  Allow  the 
crucible  to  cool,  treat  the  fused  mass  with  water,  transfer  to  a 
beaker,  allow  the  insoluble  matter  to  settle,  decant  the  clear, 
supernatant  liquid  through  a  filter,  and  treat  the  residue  with  HC1. 
Pour  the  solution  through  the  filter  to  take  up  any  iron  that  may 
have  been  suspended  in  the  liquid  decanted  through  it,  and  deter- 
mine the  iron  volumetrically  or  by  precipitation  as  sulphide  in  the 
solution  to  which  citric  acid  and  an  excess  of  ammonia  have  been 
added,  as  on  page  248.'  When  the  slag  contains  no  appreciable 
amount  of  manganese,  the  precipitation  by  sulphide  of  ammonium, 
page  277,  may  be  omitted  and  the  CaO  precipitated  at  once  from 
the  concentrated  solution. 

For  the  analysis  of  slags  that  are  not  entirely  decomposed  by 
HC1,  recourse  must  be  had  to  fusion  with  Na2CO3  and  a  little 
NaNO3,  exactly  as  described  for  the  analysis  of  clay,  page  271 
et  seq.  After  filtering  off  the  SiO2  as  directed,  page  271,  proceed 
with  the  analysis  as  described  for  slags  decomposed  by  HC1,  page 
277  et  seq.  As,  however,  the  oxalate  of  calcium  is  very  liable  to 
carry  down  sodium  salts  with  it,  it  is  always  well,  after  igniting 
the  oxalate  of  calcium,  to  dissolve  it  in  dilute  HC1,  transfer  the 
solution  to  a  platinum  dish,  dilute  to  300  c.c.  with  hot  water, 
add  an  excess  of  ammonia,  and  precipitate  boiling  by  30  c.c.  of  a 
saturated  solution  of  oxalate  of  ammonium.  Filter,  wash,  ignite, 
and  weigh  in  the  usual  manner. 

For  the  determination  of  sulphur  in  slags,  fuse  I  gramme  with 
Na2CO3  and  a  little  KNO3,  and  proceed  exactly  as  directed  for  the 
determination  of  sulphur  in  iron  ores,  page  226  et  seq.  Calculate 
the  total  sulphur  as  CaS  and  the  remainder  of  the  calcium  as  CaO. 

For  the  determination  of  alkalies,  titanic  acid,  etc.,  proceed  as 
directed  for  the  determination  of  these  substances  in  clay. 

Converter  slags,  open-hearth  slags,  refinery  slag,  tap  cinder, 
mill  cinder,  etc.,  are  analyzed  by  the  methods  described  for  the 


DETERMINATION  OF  PHOSPHORIC  ACID. 

analysis  of  iron  ores.  In  the  case  of  slags  obtained  from  the  Analysis  of 
manufacture  of  steel  by  the  basic  process,  which  usually  contain 
very  large  amounts  of  phosphoric  acid,  proceed  as  follows :  Treat 
I  gramme  of  the  finely-ground  slag  in  a  small  beaker  with  1 5  c.c. 
HC1  and  a  little  HNO3  until  it  is  decomposed.  Evaporate  to  dry- 
ness,  redissolve  in  10  c.c.  HC1  and  20  c.c.  H2O,  dilute,  filter  off, 
and  weigh  the  SiO2.  To  the  filtrate  diluted  to  500  c.c.  add  a  solu-  siO2. 
tion  of  ferric  chloride  and  a  slight  excess  of  ammonia,  if  the  pre- 
cipitate is  not  decidedly  red  in  color,  acidulate  carefully  with  HC1, 
add  more  ferric  chloride  solution,  and  then  a  slight  excess  of 
ammonia.  Add  acetic  acid  to  slight  acid  reaction,  heat  to  boiling, 
filter  and  wash  slightly  with  boiling  water,  stand  the  filtrate  aside, 
and  dissolve  the  precipitate  on  the  filter  in  HC1,  allow  the  solution 
to  run  into  the  beaker  in  which  the  precipitation  was  made,  wash 
the  filter  thoroughly  with  cold  water,  dilute  the  filtrate  to  about 
400  c.c.,  add  a  slight  excess  of  ammonia,  and  then  acetic  acid, 
boil,  and  filter  as  before.  Add  this  filtrate  to  the  first,  evaporate 
down,  and  determine  the  manganese,  calcium,  and  magnesium,  as 
directed  in  the  case  of  blast-furnace  slags,  page  277.  Dissolve  the  Mno,  Cao, 
precipitate  on  the  filter  in  HC1,  dissolving  any  iron  that  may 
adhere  to  the  beaker  in  a  few  drops  of  the  same  acid,  pour  it  on 
the  filter,  and  wash  the  beaker  and  filter  well  with  water.  Allow 
the  solution  and  washings  to  run  into  a  No.  3  beaker,  add  about 
10  grammes  of  citric  acid  and  an  excess  of  ammonia.  To  this 
solution,  which  should  be  cold,  and  should  measure  about  300  c.c. 
add,  drop  by  drop,  50  c.c.  of  magnesia  mixture,  stirring  carefully, 
without  touching  the  sides  of  the  beaker  with  the  rod.  Add  about 
one-third  the  volume  of  the  solution  of  ammonia,  allow  the  beaker 
to  stand  in  ice-water  for  some  time,  stir  vigorously  several  times, 
and  after  a  few  hours  filter  (preferably  on  a  Gooch  crucible),  wash 
with  ammonia-water  of  the  usual  strength,  ignite  carefully,  and  p^ 
weigh  as  Mg2P2O7.  Any  alumina  in  the  slag  will  be  in  the  fil- 
trate from  the  phosphate  of  ammonium  and  magnesium,  and  may 
be  determined  by  the  method  on  page  248.  Determine  the  iron 


280  ANALYSIS   OF  SLAGS. 

Feo.  volumetrically  in  a  separate  portion,  and  calculate  to  FeO.     Deter- 

mine any  other  elements  present  by  the  methods  under  "  Analysis 
of  Iron  Ores." 

Phosphoric  acid  cannot  well  be  determined  in  basic  slags  by 
fusion  with  Na2CO3,  as  phosphate  of  calcium  is  not  readily  decom- 
posed by  this  method,  and  its  employment  may  lead  to  error. 


METHOD  FOR  THE  ANALYSIS 

OF 

FIRE-SANDS. 


As  sand  contains  comparatively  very  small  amounts  of  alumina, 
lime,  and  magnesia,  and  a  very  large  amount  of  silica,  it  is  best 
to  proceed  as  follows  in  the  analysis :    Weigh  2  grammes  of  the  Treatment 
finely-ground   sand   into   a   large   platinum    crucible,   moisten   it     Tnd 
with  cold  water,  add  6  or  8  drops  of  H2SO4,  and  then  gradually     H2S°4' 
enough  HF1  to  dissolve  it.     Evaporate  to  dryness  (under  a  hood, 
of  course),  and  heat  to  redness  to  drive  off  the  H2SO4.     Allow 
the  crucible  to  cool,  add  a  little  Na2CO3,  and  fuse.     Dissolve  the 
cold  fusion  in  water,  add  an  excess  of  HC1,  evaporate  to  dryness, 
redissolve  in  HC1  and  water,  filter  from  SiO2,  and  determine  the 
A12O3,  CaO,  and  MgO  as  usual.     Ignite  i   gramme  of  the  sand  ALA,  Cao, 

and  MgO. 

and  determine  the  loss,  which  will  be  water  and  organic  matter  (if   Water 
present). 

It  is  well  to  note  that  in  the  presence  of  A12O3  it  is  almost 
impossible  to  drive  off  all  the  SiO2  by  treatment  with  HF1  and 
H2SO4,  and  the  small  amount  of  SiO2  remaining  after  this  treat- 
ment must  be  separated  as  directed  above. 

Add  together  the  percentages  of  water,  A12O3,  CaO,  and  MgO, 
subtract  the  sum  from  100,  and  call  the  remainder  SiO2.  Sl°«- 


281 


METHODS  FOR  THE  ANALYSIS 

OF 

COAL  AND   COKE. 


PROXIMATE    ANALYSIS. 

A  PROXIMATE  analysis  affords  a  very  rapid  and  comparatively 
simple  way  of  classifying  and  valuing  coal.  From  the  nature 
of  the  material,  the  determinations  cannot  be  absolute,  but  infer- 
ences may  be  drawn  from  the  relative  proportions  of  Moisture, 
Volatile  Combustible  Matter,  and  Ash.  Therefore  it  is  essential  that 
the  analysis  should  be  performed  in  such  a  way  as  to  obtain  the 
most  concordant  results.  The  series  of  experiments  carried  out 
by  Prof.  Heinrichs,*  of  the  Iowa  State  Geological  Survey,  show 
very  clearly  that  by  following  a  definite  course  of  procedure  and 
taking  a  few  simple  precautions  the  method  may  be  made  suf- 
ficiently accurate  to  accomplish  satisfactorily  the  desired  object. 
The  details,  which  should  in  all  cases  be  closely  adhered  to,  are 
as  follows :  Weigh  from  i  to  2  grammes  of  powdered  coal  into  a 
crucible,  heat  for  exactly  one  hour  in  an  air-bath  from  105°  to  110° 
C,  allow  the  crucible  to  cool,  and  weigh  it.  The  loss  of  weight 
divided  by  the  weight  of  coal  taken  and  the  result  multiplied  by 
Moisture.  ioo  gives  the  percentage  of  Moisture  in  the  coal.  Weigh  from  I 
Volatile  to  2  grammes  of  the  powdered  coal  into  a  small  platinum  crucible, 
bustibie  heat  the  crucible  with  the  cover  on  by  means  of  a  Bunsen  burner 
for  three  and  a  half  minutes,  then,  without  allowing  the  crucible 

*  Chem.  News,  xviii.  53. 
282 


ANALYSIS   OF   THE   ASH  OF  COALS.  283 

to  cool,  heat  it  for  three  and  a  half  minutes  more  at  the  highest 
temperature  obtainable  by  means  of  a  gas  blast-lamp.  Cool  and 
weigh.  Divide  the  loss  of  weight  by  the  amount  of  material  used, 
multiply  by  100,  subtract  the  percentage  of  Moisture ',  and  the 
remainder  is  the  percentage  of  Volatile  Combustible  Matter.  This 
determination  should  always  be  made  on  a  fresh  portion  of  coal,  Fresh  p°r- 

tion  to  be 

and  never  on  the  portion  used  for  the  determination  of  Moisture.        used. 

After  weighing  the  crucible  for  the  determination  of  Volatile 
Combustible  Matter  as  above,  place  it  over  a  light  in  the  position 
shown  in  Fig.  12  or  Fig.  13,  page  22,  and  burn  off  the  carbon. 
This  operation,  which  is  liable  to  be  tedious,  may  be  hastened  by 
breaking  up  and  stirring  the  mass  from  time  to  time  with  a 
platinum  rod  or  a  piece  of  stiff  wire.  It  is  necessary  to  avoid  pro- 
ducing too  strong  a  draft  in  the  crucible,  as  by  this  means  par-  Precautions 

in  burning 

tides  of  the  ash  may  be  carried  out  and  a  fictitious  value  given  to  off  car. 
the  coal  or  coke  by  the  apparent  increase  of  Fixed  Carbon  and 
corresponding  decrease  of  Ash.  When  no  particles  of  carbon  are 
apparent  in  the  ash,  allow  the  crucible  to  cool,  and  weigh  it. 
The  difference  between  this  weight  and  the  last,  divided  by  the 
weight  of  coal  taken,  and  multipled  by  100,  gives  the  percentage 
of  Fixed  Carbon.  -  ^n 

The  difference  between  the  sum  of  the  percentages  of  Water, 
Volatile  Combustible  Matter,  and  Fixed  Carbon  and  100  is  the  per- 
centage of  Ash.     The  sum  of  the  percentages  of  Fixed  Carbon  and  Ash. 
Ash   is  the  percentage  of  Coke  which  the  coal  will  yield.     The  Coke- 
appearance  of  the  coke  before  burning  off  the  Fixed  Carbon,  its 
hardness,  etc.,  are  often  valuable  indications  of  the  coking  qualities 
of  the  coal,  and  should  be  noted.     The  appearance,  color,  etc.,  of 
the  Ash  should  likewise  be  noted. 


ANALYSIS    OF    THE    ASH. 

The  ash  may  be  analyzed  by  the  method  given  for  the  analysis 
of  the  Insoluble  Silicious  Matter  in  Iron  Ores,  page  239. 


284 


ANALYSIS   OF  COAL   AND    COKE. 


DETERMINATION    OF   SULPHUR. 


Fusion  with          Weigh  out  I  gramme  of  the  finely-ground  coal  or  coke,  and 

Na2CO3 

and  mix  it  thoroughly,  by  grinding  in  a  large  agate  or  porcelain  mor- 

tar, with  10  grammes  of  dry  Na2CO3  and  6  grammes  of  KNO3. 
During  the  mixing  it  is  well  to  have  the  mortar  on  a  large  sheet 
of  white  glazed  paper,  to  catch  any  particles  that  may  be  thrown 
from  it.  Transfer  the  mixture  to  a  large  platinum  crucible,  clean 
the  mortar  by  grinding  a  little  Na2CO3  in  it,  transfer  this  and  any 
particles  that  may  be  on  the  paper  to  the  crucible,  cover  the 
latter  with  a  lid,  and  place  it  on  a  triangle  over  a  Bunsen  burner. 
Heat  the  crucible  very  carefully,  and  raise  the  heat  very  slowly, 
cautiously  removing  the  lid  of  the  crucible  from  time  to  time  to 
see  that  the  fusion  does  not  boil  over.  It  is  very  necessary  that 
none  of  the  fused  sodium  or  potassium  salts  be  allowed  to  get  on 
the  outside  of  the  crucible,  for  they  will  certainly  absorb  sulphuric 
or  sulphurous  acid  from  the  burned  gas,  and  thus  vitiate  the  analy- 
sis. When  the  mass  in  the  crucible  is  in  a  tranquil  state  of  fusion, 
run  it  up  on  the  sides  of  the  crucible,  allow  it  to  cool,  treat  it  with 
hot  water,  and  wash  it  out  into  a  small  clean  beaker.  Filter  from 
the  insoluble  matter,  acidulate  the  filtrate  with  HC1,  and  evaporate 
to  dryness.  Redissolve  in  water  with  a  few  drops  of  HC1,  filter, 
dilute  the  filtrate  to  about  500  c.c.,  heat  to  boiling,  and  add  10-20 
c.c.  solution  of  chloride  of  barium.*  Allow  the  precipitated  sulphate 

Washing  the  of  barium  to  settle,  decant  the  clear,  supernatant  fluid  through  a 

of  barium,  filter  or  through  a  felt  on  a  Gooch  crucible,  heat  the  precipitate 

with  a  solution  of  acetate  of  ammonium,t  transfer  it  to  the  filter, 

wash  well  .with  hot  water,  dry,  ignite,  and  weigh  as  BaSO4,  which, 

Method  of     multiplied  by   .13756,   gives  the  weight  of  S.     The  time  of  the 

ingthe       operation  may  often  be  very  much  shortened  by  adding  an  excess 

lon>    of  ammonia  to  the  acidulated  filtrate  of  the  aqueous  solution  of 

the  fusion,  and  boiling  the  solution  while  passing  through  it  a 

rapid  current  of  carbonic  acid  gas.     This  precipitates  the  silica, 

*  See  page  51.  f  See  page  45. 


DETERMINATION  OF  SULPHUR. 


285 


alumina,  etc.,  and,  after  filtering  this  off,  acidulate  by  HC1,  and 
precipitate  the  sulphate  of  barium  as  above  directed. 

A  blank  determination,  using   the   same  amount  of  Na2CO3,  correction 
KNO3,  and  HC1,  should  always  be  made  with  every  new  lot  of     reagents, 
reagents,  and  the  amount  of  BaSO4  found,  subtracted  from  the 
amount  of  BaSO4  in  every  analysis  before  calculating  the  amount 
of  S  in  the  coal  or  coke. 

Besides  the  method  given  above,  Eschka's*  method  is  very  Eschka's 
often  used.  It  is  essentially  as  follows :  Weigh  out  I  gramme  of 
the  finely-ground  sample,  and  mix  it  thoroughly  in  a  mortar  with 
I  gramme  of  calcined  magnesia  and  .5  gramme  of  dry  carbonate 
of  sodium,  transfer  the  mixture  to  a  crucible,  and  heat  it  over  a 
Bunsen  burner,  having  the  crucible  inclined  in  such  a  way  that  the 
flame  may  be  applied  to  the  bottom  of  the  crucible,  so  that  the  heat, 
a  dull  red,  shall  extend  only  about  one-third  up  from  the  bottom. 
Stir  the  mixture  every  few  minutes  with  a  platinum  wire  until  the 
carbon  is  burned  off  and  the  ash  is  a  dull  yellow.  This  will  gen- 
erally require  about  one  hour.  Allow  the  crucible  to  cool,  add  to 
the  mixture  about  I  gramme  of  nitrate  of  ammonium,  mix  it  in 
thoroughly  with  a  glass  rod,  place  the  lid  on  the  crucible,  and  heat 
it  cautiously  until  the  nitrate  of  ammonium  is  decomposed  and 
the  crucible  is  raised  to  a  bright  red  heat.  Allow  it  to  cool,  treat  it 
with  hot  water,  and  transfer  the  contents  to  a  beaker.  Filter  from 
the  insoluble  matter,  acidulate  the  filtrate  with  HC1,  and  determine 
the  S  by  precipitation  as  BaSO4  in  the  usual  way. 

In    reporting   the    results    of  a   coal    analysis    the   S   should  Method  of 
always  be  reported  as  a  separate  matter,  and  no  attempt  should     [ngThe 
be  made  to  distribute  it  between  the  Volatile  Combustible  Matter, 
Fixed  Carbon,  and  Ash.     The  reason  for  this  is  obvious  when  we     coal- 
consider  the  conditions  in  which  S  exists  in  coal,  and  the  diffi- 
culty which  attends  any  attempt  to  determine  the  amount  existing 
in  any  one  condition. 

*  Chem.  News,  xxi.  261. 


286  ANALYSIS   OF  COAL   AND    COKE. 

Condition  Sulphur  is  known  to  exist  in  coal  in  three  conditions, — as  a 

s  exists  metallic  sulphide,  such  as  pyrites ;  as  sulphate  of  calcium  or 
barium ;  and  as  a  sulphuretted  hydrocarbon.  In  a  proximate 
analysis  of  coal  about  one-half  the  sulphur  in  any  pyrites  present 
and  all  the  sulphur  existing  as  a  sulphuretted  hydrocarbon  are 
probably  driven  off  with  the  Volatile  Combustible  Matter.  The  rest 
of  the  sulphur  from  the  pyrites  is  oxidized  and  driven  off  during 
the  burning  of  the  Fixed  Carbon  (sulphate  of  iron  being  easily 
decomposed  at  a  bright  red  heat)  unless  the  sulphuric  acid 
formed  is  taken  up  by  an  alkali  or  alkaline  earth. 

Determina-  The  nearest  approach  we  can  make  to  a  determination  of  the 

conditions,  conditions  in  which  the  sulphur  exists  in  any  coal  is  to  make  a 
determination  of  the  total  sulphur  by  fusion,  and  a  determination 
of  the  sulphuric  acid  in  the  ash.  By  subtracting  the  S  found  by 
the  latter  determination  from  the  total  S  the  difference  may  be 
taken  to  represent  the  amount  existing  as  S  (in  the  form  of  sul- 
phide), and  the  amount  found  in  the  ash  as  that  existing  as  SO3 
(in  the  form  of  sulphate).  These  results  will  be  correct  if  the 
coal  contains  no  carbonates  of  the  alkalies  or  alkaline  earths. 


DETERMINATION    OF   PHOSPHORIC    ACID. 

Burning  off          Burn  off  io  grammes  of  the  coal    or  coke  in  a  crucible,  or, 

the  coal 

or  coke,  as  in  anthracite  coal  or  coke  this  is  a  very  tedious  operation,  burn 
it  off  in  a  large  platinum  boat  in  a  tube  in  a  current  of  oxygen. 
A  boat  4  inches  (102  mm.)  long,  and  wide  enough  to  fit  in  a  tube 
y^  of  an  inch  (19  mm.)  in  diameter,  will  hold  io  grammes  very 
easily,  and  by  its  use  this  amount  of  coke  or  anthracite  coal  may 
be  burned  off  in  a  current  of  oxygen  in  about  one  and  a  half 
hours.  Treat  the  ash  with  HC1  to  dissolve  any  phosphate  of  cal- 
cium, filter,  and  wash  well  with  water.  Stand  the  filtrate  aside, 
dry,  ignite,  and  fuse  the  insoluble  matter  with  Na2CO3.  Dissolve 


DETERMINATION  OP   PHOSPHORIC  ACID. 

in  water,  filter  from  the  insoluble  matter,  acidulate  the  filtrate  with 
HC1,  and  evaporate  to  dry  ness.  Redissolve  in  water  and  a  little 
HC1,  filter,  add  this  filtrate  to  the  HC1  filtrate  from  the  first  treat- 
ment of  the  ash,  add  a  little  ferric  chloride  solution  and  a  slight 
excess  of  ammonia.  Acidulate  with  acetic  acid,  heat  to  boiling,  boil 
for  a  few  minutes,  filter,  and  wash  the  precipitate  once  or  twice  with 
boiling  water.  Dissolve  the  precipitate  in  HC1,  evaporate  nearly 
to  dryness,  add  citric  acid,  magnesia  mixture,  and  ammonium, 
and  precipitate  as  directed  on  page  85.  Filter  off,  ignite,  and 
weigh  the  Mg2P2O7  as  there  directed.  Or,  after  dissolving  the 
acetate  precipitate,  as  above,  in  HC1,  evaporate  down,  and  pre- 
cipitate the  P2O5  by  molybdate  solution,  as  directed  on  page  89 
et  seq. 


METHODS    FOR   THE    ANALYSIS 

OF 

GASES. 


THE  technical  analysis  of  gases  is  of  growing  importance,  and 
a  knowledge  of  the  methods  of  analysis  and  of  the  manipulation 
involved  is  now  generally  necessary  to  the  iron  chemist.  For  ease 
of  manipulation,  and  for  the  accuracy  of  the  results  obtained  by 
its  use,  Hempel's  form  of  apparatus  is  generally  to  be  preferred. 

apparatus. 

It  consists  essentially  of  a  burette  for  holding  and  measuring  the 
gas  B,  Fig.  101  (the  modified  Winkler's  gas-burette),  and  a  pipette, 
G,  Fig.  101,  which  holds  the  reagent.  By  means  of  the  level-tube 
A,  filled  with  water,  the  gas  is  forced  into  the  pipette,  where  it  is 
brought  in  contact  with  the  reagent  and  afterwards  returned  to  the 
burette  and  measured.  By  the  use  of  a  series  of  these  pipettes, 
each  filled  with  a  separate  reagent,  the  various  constituents  of  the 
gas  under  examination  are  absorbed  and  their  volumes  estimated. 

COLLECTING    SAMPLES. 

Fig.  98  shows  a  very  simple  method  for  taking  a  sample  of  gas 
for  analysis.  The  porcelain  tube  A  passes  through  the  brick-work 
into  the  flue  through  which  the  gas  is  carried.  In  the  sketch  a 
portion  of  the  porcelain  tube  is  cut  away,  to  show  the  loose  fila- 
ments of  asbestos  with  which  the  tube  is  filled  to  keep  dust  or 
tarry  matter  from  entering  the  burette.  This  asbestos  must  be  put 

in  very  loosely,  or  else  it  will  pack  and  interfere  with  the  free  pas- 
288 


COLLECTING   SAMPLES. 


289 


sage  of  the  gas.  Where  the  gas,  as  from  a  producer,  etc.,  is 
constantly  examined,  it  is  very  convenient  to  have  a  valve  fitted 
permanently  to  an  iron  pipe  screwed  or  cemented  into  the  flue, 
into  which  the  porcelain  tube  may  be  fastened  by  means  of  a 
rubber  or  asbestos  *  stopper.  A  glass  tube  of  about  ^  inch 
(6  mm.)  diameter  is  fitted  into  the  outer  end  of  the  porcelain  tube 


FIG.  98. 


A. 


)a 


A,  Fig.  98,  by  means  of  a  rubber  or  asbestos  stopper,  and  this 
glass  tube  is  connected  by  means  of  the  rubber  tube  C  with  the 
opening  at  the  lower  end  of  the  burette  d.     If  the  gas  is  under  Taking  the 
pressure  (as  is  rarely  the  case),  it  is  only  necessary  to  open  the     In™**:* 
stopcocks  and  allow  it  to  pass  through  the  burette  until  the  air 
is  entirely  displaced.     Usually,  however,  it  is  necessary  to  draw 
the  gas  through ;  and  the  little  india-rubber  pump  D  attached  to 


*  See  page  144. 
19 


290 


ANALYSIS   OF  GASES. 


Aspirator 
for  draw- 
ing gas 
through 
the  bu- 
rette. 


Compress- 
ing the 
gas  in 
the  bu- 
rette. 


Other  ves- 
sels for 
collecting 
samples. 


FIG.  99. 


the  capillary  tube  at  the  upper  end  of  the  burette  is  very  useful 
for  this  purpose.  It  is  fitted  with  a  simple  valve  at  each  end,  so 
that  by  compressing  the  bulb  in  the  hand  its  contents  are  dis- 
charged through  the  outer  end  while  the  pressure  closes  the  valve 
at  the  burette  end.  When  the  bulb  is  released  it  resumes  its  shape, 
the  tension  closing  the  outer  valve  and  opening  the  one  towards 
the  burette,  through  which  the  contents  of  the  latter  are  drawn 
into  the  bulb.  A  bulb  of  the  usual  size  will  empty  a  100  c.c. 
burette  in  about  three  strokes.  In  taking  a  sample  of  gas,  turn 
the  3-way  stopcock  b  so  that  the  passage  is  open  through  into  the 
burette,  open  the  stopcock  a  at  the  upper  end  of  the  burette,  and 
pump  the  gas  th-rough  slowly  for  five  or  six  minutes.  Close  the 

upper  stopcock  #,  compress  the  rubber 
tube  C  between  the  thumb  and  fingers 
of  the  left  hand,  and,  holding  the  tube 
with  the  other  hand,  slide  the  left  hand 
towards  the  burette.  This  will  com- 
press the  gas  in  the  burette,  and  by 
closing  the  stopcock  b  while  the  tube 
C  is  thus  held  the  gas  in  the  burette 
will  be  under  pressure.  In  closing  b, 
it  must  be  turned  so  that  the  passage  is  open  from  d  out  through 
c,  as  shown  in  Fig.  99.  Remove  the  burette  to  the  laboratory, 
attach  the  rubber  tube  C  of  the  level-tube  A,  Fig.  101,  to  the  end 
of  the  burette,  loosen  the  pinchcock  E,  and  allow  the  water  to 
run  through  until  it  comes  out  through  the  rubber  tube  on  the 
end  of  the  stopcock.  Close  E,  and  allow  the  burette  and  gas  to 
attain  the  temperature  of  the  laboratory.  Samples  of  gas  for 
analysis  may  also  be  taken  in  glass  tubes  drawn  out  at  the  ends 
and  closed  by  rubber  tubes  and  pinchcocks  or  pieces  of  glass  rod. 
When  the  sample  is  to  be  taken  to  a  distance,  it  may  often  be  col- 
lected in  a  metal  vessel  with  conical  ends  and  tubes  with  well- 
ground  stopcocks.  Glass  vessels  of  the  proper  shape,  holding 
from  half  a  litre  to  one  litre,  and  fitted  with  glass  stopcocks  and 


METHOD    OF  FILLING   PIPETTES.  2gr 

capillary  tubes  made  for  this  purpose,   may  be  purchased  from 
dealers  in  chemical  glass-ware.     From  these  vessels  or  tubes  the 
gas  may  be  transferred  to  the  burette  by  attaching  to  one  outlet  a  Transfer- 
tube  filled  with  water  and  joined  to  the  burette,  likewise  filled  with     burette.'  " 
water,  placing  the  other  end  of  the  vessel  in  water,  lowering  the 
level-tube,  and  drawing  the  gas  into  the  burette. 


REAGENTS    FOR    THE    PIPETTES. 

Blast-furnace  gas,  producer  gas,  and,  in  general,  gases  made  Composition 
by  drawing  or  forcing  atmospheric  air  through  coal  or  coke,  con- 
tain varying  amounts  of  carbon  dioxide  (CO2),  oxygen  (O),  carbon 
monoxide  (CO),  hydrogen  (H),  methane,  or  marsh  gas  (CH4),  and 
nitrogen  (N).     The  best  absorbents  are  caustic  potassa  for  CO2,   Absorbents, 
pyrogallol  for  O,  and  cuprous  chloride  in  HC1  for  CO.     Hydro- 
gen is  determined  by  ignition  with  excess  of  oxygen  over  palla- 
dium sponge,  and  marsh  gas  by  ignition    in   a  tube  filled  with 
cupric  oxide.     The  pipettes  required,  therefore,  are  a  simple  pipette 
(G,  Fig.  100)  filled  with  caustic  potassa,  1.27  sp.  gr.,  for  absorbing 
CO2,  which  is  readily  filled  by  placing  in  the  large  tube  of  the  Method  of 
pipette  a  small  glass  tube,  which  extends  down  to  the  bottom  of      simpfea 
the  bulb  and  is  connected  outside  with  a  small  glass  funnel  by     P'Pette- 
means  of  a  piece  of  gum   tubing.     Pour  the  caustic  potassa  in  caustic 
through  the  funnel  until  the  large  bulb  of  the  pipette  and  the  tube     JJJ^T 
connecting  the  two  bulbs  are  filled  with  the  liquid.     Draw  the 
liquid  into  the  capillary  tube  until  it  reaches  to  within  a  very  short 
distance  of  the  rubber  tube  on  the  end  of  the  capillary,  and  close 
the  rubber  tube  with  a  piece  of  glass  tubing  or  a  pinchcock,  as 
shown  in  the  sketch  of  the  composite  pipette,  Fig.  100. 

A  composite  pipette  (Fig.   106)  containing  pyrogallol  for  ab-  Method  01 

filling  a 

sorbing  oxygen  is  filled  as  follows  :  Dissolve  30  grammes  of  pyro-      composite 
gallic  acid  in  75  c.c.  of  water,  attach  a  funnel  to  the  capillary  tube 


20/2  ANALYSIS   OF  GASES. 

of  the  pipette  by  a  piece  of  rubber  tubing,  and  fill  it  with  the  solu- 
tion.    Attach  a  piece  of  rubber  tubing  to  the  other  tube  of  the 

pipette,  and  by  gentle  suction  exhaust  the 
FIG.  loo. 

air ;  this  will  cause  the  liquid  to  run  rap- 
idly through  the  capillary  tube  into  the 
pipette.  Keep  the  funnel  full  until  the 
liquid  which  is  drawn  through  the  large 
bulb  into  the  second  bulb  fills  the  latter 
to  an  inconvenient  extent,  then  stop  the 
suction,  and  very  carefully  blow  the  liquid  back  into  the  large 
bulb.  Fill  the  funnel  again,  and  exhaust  the  air  gently  as 
before.  Repeat  this  until  all  the  solution  of  pyrogallic  acid  has 
been  drawn  in,  and  then  with  the  same  precautions  draw  in  a 
solution  of  caustic  potassa,  1.27  sp.  gr.,  until  the  large  bulb  and 
the  tube  connecting  the  large  bulb  and  the  second  bulb  are  filled 
with  the  liquid,  which  is  now  an  alkaline  solution  of  pyrogallate 
Pyrogaiioi  of  potassium.  Close  the  capillary  tube  as  directed  for  the  caustic 
potassa  pipette,  page  291.  Insert  the  small  tube  and  funnel  in  the 
large  tube  of  the  composite  pipette,  as  directed  on  page  291  for 
filling  the  simple  pipette,  and  pour  a  little  water  into  the  last  bulb 
of  the  composite  pipette.  The  amount  of  water  poured  in  should 
not  be  sufficient  to  fill  the  third  bulb,  for  the  pyrogallol  rapidly 
absorbs  the  oxygen  of  the  air  in  the  second  bulb,  and  this  contrac- 
tion causes  the  water  poured  into  the  last  bulb  to  rise  in  the  third 
bulb.  Therefore  the  amount  of  water  should  be  small  enough  to 
permit  small  bubbles  of  air  to  pass  through  to  supply  the  contrac- 
tion in  the  second  bulb,  and  large  enough  to  avoid  emptying  the 
third  bulb  when  the  gas  during  an  analysis  is  forced  through  the 
capillary  into  the  large  bulb  of  the  pipette.  The  amount  of  pyro- 
gallate of  potassium  from  30  grammes  of  pyrogallic  acid  is  suffi- 
Absorbing  cient  to  absorb  nearly  1 500  c.c.  of  pure  oxygen,  so  that  a  com- 
of^yr^  posite  pipette  filled  in  this  way,  and  securely  sealed  by  the  water 
in  the  third  and  fourth  bulbs,  will  last  for  almost  an  indefinite 
number  of  analyses. 


DETAILS   OF   THE  ANALYSIS. 


293 


Another  composite  pipette  for  absorbing  carbon  monoxide  is  cuprous 
filled,  as   above  described,   with  a  saturated  solution  of  cuprous     pipette6 
chloride  in  HC1,  i.i  sp.gr.,  and  sealed  with  water.     Each  pipette  Marking 

pipettes. 

should    be    distinctly  labelled  with  the  name   of  the  reagent,  so 
that  no  mistake  can  be  made  in  using  them. 

It  is  worthy  of  note  that  the  absorption  of  CO  by  cuprous  Absorption 
chloride  is  purely  mechanical,  and  is  never  absolutely  perfect,  so  cuprous 
that  a  small  amount  of  CO  invariably  remains  in  the  gas  after 


never 


treatment  in  the  cuprous  chloride  pipette.  Moreover,  whenever  Perfect- 
a  gas  absolutely  free  from  CO  is  treated  in  a  cuprous  chloride 
pipette  (which  has  been  previously  used  to  absorb  CO)  and  re- 
turned to  the  burette,  it  will  be  found  to  have  increased  in  volume, 
and  subsequent  combustion  in  a  palladium  tube  will  yield  an 
amount  of  CO2  corresponding  to  this  increase  counted  as  CO. 
If  this  fact  is  overlooked,  the  CO  left  in  the  gas  will  be  counted  as 
methane  if  a  determination  of  this  gas  is  made  in  the  usual  course 
of  the  analysis. 

A  composite  pipette  filled  with  bromine-water  to  absorb  Bromine 
ethylene  (C2H4)  is  sometimes  used,  as  this  gas  has  been  found 
in  the  gases  from  blast-furnace  and  producers  using  bituminous 
coal.  But  the  amount  of  ethylene  is  very  small,  and  a  separate 
determination  is  rarely  made,  any  small  amount  being  absorbed 
and  determined  as  CO. 


ANALYSIS    OF    THE    SAMPLE. 

The  burette  containing  the  gas,  with  the  level-tube  filled  with 
water  attached,  as  mentioned  on  page  290,  having  attained  the 
temperature  of  the  laboratory,  raise  the  level-tube  and  open  the 
3-way  stopcock  so  that  the  passage  is  open  for  the  water  to  enter 
the  burette.  If  the  gas  is  shown  to  be  under  a  slight  pressure,  by 
raising  or  lowering  the  burette  bring  the  water  just  to  the  stop- 
cock (if  the  burette  is  graduated  to  read  100  c.c.  from  stopcock  to 
stopcock,  otherwise  bring  the  water  to  the  o  mark),  and  close  the 


294 


ANALYSIS   OF  GASES. 


Reading  the 
volume  of 
gas  in  the 
burette. 


FIG.  101. 


Method  of 
connect- 
ing the 
burette 
and  the 
pipette. 


stopcock.  Then  open  the  upper  stopcock  for  an  instant  to  allow 
the  gas  to  assume  the  pressure  of  the  atmosphere.  Now  open  the 
3-way  stopcock  to  allow  the  water  to  enter  the  burette,  hold  the 
level-tube  so  that  the  water  in  the  tube  and  that  in  the  burette  are 
at  the  same  level,  and  observe  the  reading  of  the  burette.  It  is  a 
very  simple  matter  in  this  way  to  get  exactly  100  c.c.  of  gas,  which 
very  materially  simplifies  the  calculations.  Connect  the  burette 

with  the  pipette  containing  caus- 
tic potassa  by  means  of  the  capil- 
lary connecting-tube,  as  shown  in 
Fig.  101.  Some  little  skill  is  neces- 
sary in  making  this  connection ; 
the  best  way  to  arrange  it  is  as 
follows :  Attach  one  end  of  the 
capillary  connecting-tube  to  the 
top  of  the  burette  by  a  piece  of 
gum  tubing,  wiring  it  if  neces- 
sary, then  compress  between  the 
thumb  and  forefinger  of  one 
hand  the  rubber  tube  on  the 
capillary  of  the  pipette  for  its 
entire  length  above  the  pinch- 
cock  (as  shown  in  Fig.  100), 
then  carefully  introduce  the  end 
of  the  capillary  connecting-tube 
into  the  end  of  the  rubber  tube, 
and  release  the  rubber  tube.  If 
this  is  carefully  done,  the  walls 
of  the  rubber  tube  between  the 
pinchcock  and  the  end  of  the 
capillary  will  remain  in  contact, 
showing  that  no  air  has  been 
admitted.  Force  the  end  of  the  capillary  tube  down  to  the  pinch- 
cock,  and  open  the  latter,  allowing  it  to  remain  over  the  capil- 


DETERMINATION  OF  ETHYLENE.  295 

lary,  as  shown  in  Fig.  102.  The  apparatus  will  now  be  in  the 
position  shown  in  Fig.  101.  Open  the  upper  stopcock  of  the 
burette,  and  then  turn  the  3 -way  stopcock  D  carefully  to  admit 
the  water  from  the  level-tube  into  the  burette.  As  the  water 
enters  the  burette  the  gas  is  forced  over  into  the  pipette  G. 
Allow  the  water  to  fill  completely  the  burette  B  and  to  enter  the 
capillary  tube  F  and  fill  it  as  far  as  the  rubber  connection  between 
it  and  the  capillary  tube  of  the  pipette  G.  Close  the  upper  stop-  Determina- 
cock  of  the  burette,  place  the  pinchcock  on  the  rubber  tube  be-  co>2° 
tween  the  capillary  connecting-tube  and  the  pipette,  and  remove 
the  capillary  connecting-tube  F  from  the  rubber  tube  of  the 
pipette,  leaving  it  attached  to  the  burette.  Take  the  pipette  from 
the  stand  and  shake  it,  to  promote  the  absorption  of  the  CO2, 
which  will  require  only  a  minute  or  two.  Replace  the  pipette, 
attach  the  capillary  connecting-tube  F  as  before,  remove  the 
pinchcock,  place  the  level-tube  A  on  the  floor,  open  the  upper 
stopcock  of  the  burette,  and  allow  the  water  to  run  from  the 
burette  B  into  the  level-tube  A,  drawing  the  gas  from  the  pipette 
G  into  the  burette  B.  When  the  caustic  potassa  solution  has  run 
back  so  as  to  fill  the  large  bulb  and  the  capillary  of  the  pipette 
almost  to  the  rubber  connection,  close  the  upper  stopcock  of  the 
burette  B  quickly,  replace  the  pinchcock  on  the  rubber  tube  of  the 
pipette  G,  detach  the  capillary  connecting-tube  F  from  the  pipette, 
hold  the  level-tube  A  and  the  burette  B  together  to  get  the  water 
on  an  exact  level,  and  take  the  reading  of  the  burette.  The  differ- 
ence between  this  reading  and  the  original  reading  will  be  the 
number  of  c.c.  of  CO2  absorbed ;  and  if  the  original  reading  was 
100  c.c.,  each  c.c.  absorbed  will  be  one  per  cent,  of  CO2  in  the 
gas.  If  any  other  volume  of  gas  was  originally  used,  divide 
the  number  of  c.c.  absorbed  by  the  number  originally  used,  mul- 
tiply this  by  100,  and  the  result  is  the  percentage  of  CO2  in 
the  gas. 

If  ethylene  is  to  be  determined,  pass  the  gas  into  the  bromine-  Determina- 

tion  of 

water  pipette,  back  into  the  burette,  then  into  the  caustic  potassa     c2H4. 


296 


ANALYSIS   OF  GASES. 


Determina- 
tion of  O. 


Determina- 
tion of 
CO. 


Determina- 
tion of  H. 


Description 
of  the 
apparatus. 


Transfer- 
ring a 
portion 
of  the 
unab- 
sorbed 
gas. 


pipette  to  absorb  any  bromine  fumes,  finally  back  into  the  burette, 
and  take  the  reading  as  before.  The  contraction  is  ethylene. 

Now  pass  the  gas  into  the  pyrogallol  pipette,  shake  the  latter 
gently  for  four  or  five  minutes  to  promote  the  absorption  of  the 
oxygen,  return  the  gas  to  the  burette,  and  note  the  reading.  The 
contraction  from  the  last  reading  is  O. 

Pass  the  gas  in  the  same  manner  into  the  cuprous  chloride 
pipette,  detach  and  shake  the  latter  gently  at  short  intervals  for 
five  or  six  minutes  to  promote  the  absorption  of  the  CO,  return 
the  gas  to  the  burette,  and  take  the  reading.  The  contraction 
from  the  last  reading  is  the  CO  absorbed  by  cuprous  chloride. 
To  determine  the  remaining  CO  and  the  H,  the  gas  is  mixed  with 
oxygen  and  burned  over  spongy  palladium.  Fig.  icy  shows  the 
arrangement  of  the  apparatus.  A  is  the  palladium  tube,  B  the 
burette,  C  a  pipette  filled  with  water,  D  a  small  gas-burner  for 
heating  the  palladium  tube,  and  E  the  gas-pipe  attached  to  the 
wood-work  of  the  pipette  and  connected  by  a  rubber  tube  with 
a  supply  of  gas.  Instead  of  a  gas-burner  for  heating  the  palla- 
dium tube  a  small  brass  spirit-lamp  may  be  used,  which  is  fastened 

to  the  pipette-stand  by  a  clamp  in  such 
a  position  as  to  bring  the  flame  under 
the  palladium  tube.  With  any  ordinary 
furnace  or  producer  gas  which  con- 
tains 50  per  cent,  and  upwards  of  nitro- 
gen, the  best  plan  is  to  attach  an  oxy- 
gen-cylinder to  the  top  of  the  burette, 
using  a  capillary  tube  and  rubber  con- 
nections, and  fill  the  latter  with  oxygen 

gas.  With  water-gas,  or  when  a  supply  of  oxygen  is  not  available, 
it  is  necessary  to  transfer  a  portion  of  the  unabsorbed  gas  in  the 
burette  to  another  burette,  and  then  to  admit  air  to  the  first  burette 
until  it  is  nearly  filled.  Of  course  it  makes  the  calculation  a  little 
more  complicated  to  change  the  volume  of  the  gas  in  this  way 
during  the  progress  of  an  analysis,  but  in  the  case  of  nearly  pure 


FIG.  102. 


DETERMINATION  OF  HYDROGEN.  297 

water-gas  the  use  of  oxygen  alone  would  probably  lead  to  an 
explosion,  while  with  other  gases,  in  the  absence  of  a  supply  of 
oxygen,  simply  filling  the  burette  with  air  without  letting  out  any 
of  the  gas  might  not  admit  enough  oxygen  to  burn  the  hydrogen. 
After   transferring   a   portion    of  the    unabsorbed    gas,    read   the 
burette  carefully  to  get  the  volume  of  gas  taken  for  combustion, 
and  then  Divide  the  volume  of  gas  taken  for  combustion  by  the  total  Calculating 
volume  unabsorbed,  and  multiply  by  the  amount  originally  taken  for     of  gas 
analysis ;  the  result  is  the  number  of  c.c.  of  the  original  gas ,  to 
which  the  amount  taken  for  combustion  corresponds. 

After  admitting  air  to  the  burette,  which  is  done  by  standing 
the  level-tube  on  the  floor  while  the  burette  is  on  the  table, 
opening  the  3-way  stopcock  so  that  the  water  may  run  into  the 
level-tube,  and  opening  the  upper  stopcock  of  the  burette  until  the 
proper  amount  of  air  has  been  drawn  in,  take  the  reading  of  the 
burette  with  care.  Connect  the  apparatus  as  shown  in  Fig.  102, 
light  the  gas-jet  D,  open  the  upper  stopcock  of  the  burette  B, 
and  by  opening  very  carefully  the  3-way  stopcock  of  the  burette 
cause  the  gas  to  pass  very  slowly  into  the  pipette  C.  The  palla- 
dium tube  should  not  be  heated  to  redness,  but  to  a  temperature 
just  below  a  dark-fed  heat.  It  is  very  necessary  to  avoid  carrying  precautions 
over  any  water  into  the  hot  palladium  tube,  as  it  would  be  certain  "oa^old7 
to  crack  it,  and  for  this  reason  it  is  well  to  see  that  the  capillary  breaki"s 

'          the  pal- 
tube  above  the  stopcock  of  the  burette  and  both  capillary  ends  of      ladium 

the  palladium  tube  are  dry  before  making  the  connections.  Any 
little  moisture  may  be  removed  by  means  of  a  very  fine  wire 
wrapped  with  thread.  As  the  water  from  the  combustion  of  the  H 
in  the  palladium  is  liable  to  condense  in  the  end  of  the  tube  near 
the  pipette,  it  is  always  well  to  warm  this  gently  with  the  flame 
of  a  small  spirit-lamp  or  a  piece  of  glowing  charcoal,  so  as  to  drive 
all  the  moisture  into  the  pipette,  and  thus  prevent  its  being  carried 
into  the  hot  part  of  the  palladium  tube  when  the  gas  is  returned 
into  the  burette.  When  the  water  has  risen  in  the  burette  just 
above  the  upper  stopcock,  lower  the  level-tube  and  draw  the  gas 


2gS  ANALYSIS   OF  GASES. 

back  very  slowly  into  the  burette.  When  the  water  in  the  pipette 
has  risen  to  the  usual  position  in  the  capillary,  replace  the  pinch- 
cock  on  the  rubber  connection  between  the  palladium  tube  and 
the  capillary  tube  of  the  pipette,  extinguish  the  light  under  the 
palladium  tube,  and,  when  the  latter  is  cold,  close  the  upper  stop- 
cock of  the  burette,  detach  the  apparatus,  open  the  3-way  stop- 
cock fully,  and  take  the  reading  of  the  burette. 

Now,  if  there  were  no  CO  present  in  the  gas  before  the  com- 
bustion, the  contraction  would  be  due  to  the  condensation  of  the 
H2O  formed  by  the  combustion  of  the  H,  and,  as  2  volumes  of  H 
unite  with  I  volume  of  O  to  form  H2O,  f  of  the  contraction  would 
be  H.  In  the  presence  of  CO,  however,  there  is  an  additional  con- 
traction beyond  that  caused  by  the  formation  of  H2O,  due  to  the 
fact  that  2  volumes  of  CO  uniting  with  I  volume  of  O  form  2 
volumes  of  CO2.  By  absorbing  the  CO2  in  the  caustic  potassa 
pipette,  and  then  reading  the  burette,  the  second  contraction  is  the 

Calculating    volume  of  the  CO2,  which  is  the  volume  of  the  CO.     The  first  con- 
co.          traction,  then,  is  f  of  the  H  -f  \  the  CO,  and  the  'second  contrac- 
tion being  the  volume  of  the  CO,  it  may  be  stated  thus : 

first  contraction  =  |-H  -f-  \  second  contraction, 
or  -|H  =  first  contraction — -^  second  contraction; 

multiplying  by  |-, 

H=f  first  contraction  —  -J  second  contraction. 
Divide  the  number  of  c.c.  of  H  and  CO  respectively  as  found 
above  by  the  number  of  c.c.  of  the  original  gas  to  which  the 
amount  taken  for  combustion  is  equivalent,  multiply  by  100,  and 
the  result  is  the  percentage  of  H  and  CO.  This  percentage  of  CO 
is  to  be  added  to  the  percentage  found  by  absorption  in  cuprous 

Total  co.      chloride,  and  the  result  is  the  total  CO. 

Determina-  There  remain  now  in  the  burette  only  nitrogen  and  methane. 

CH4.  The  latter  can  be  properly  burned  only  at  a  red  heat  in  contact 
with  oxide  of  copper,  forming  H2O  and  CO2.  By  absorbing  the 
CO2  in  a  solution  of  caustic  baryta,  standardized  by  a  normal  solu- 
tion of  oxalic  acid,  and  then  titrating  the  caustic  baryta,  the  volume 


DETERMINATION  OF  METHANE. 

of  CH4  is  at  once  indicated.  As  the  normal  solution  of  oxalic  acid 
indicates  the  volume  of  CH4  at  760  mm.  of  barometric  pressure 
and  o°  C.  of  temperature,  the  thermometer  and  barometer  must  be 
noted,  and  the  correction  made  according  to  the  table  (Table  V.). 

Dissolve  5.6314  grammes  of  crystallized  oxalic  acid  in  I  litre 
of  water.  I  c.c.  of  this  solution  indicates  i  c.c.  CO2,  or  I  c.c. 
CH4,  at  760  mm.  barometric  pressure  and  o°  C.  Dissolve  14.0835 
grammes  of  crystallized  hydrate  of  barium  in  I  litre  of  water. 
I  c.c.  of  this  solution  is  equal  to  about  I  c.c.  of  the  oxalic  acid 
solution. 

The  apparatus  for  the  determination  is  shown  in  Fig.  103.  It 
consists  of  a  porcelain  tube,  EE,  in  the  combustion-furnace  F ;  the 

FIG.  103. 


299 


porcelain  tube  is  nearly  filled  with  coarse  oxide  of  copper  between 
loose  plugs  of  asbestos,  or  with  a  roll  of  oxidized  copper  wire  (see 
page  142).  The  forward  end  is  connected  with  two  absorption- 
bottles,  G,  G,  containing  caustic  baryta  solution.  These  bottles  are 
of  such  a  size  that  25  c.c.  will  fill  them,  so  that  the  gas  in  bubbling 


standard 


acid  and 

caustic 

baryta. 


3°° 


ANALYSIS   OF  GASES. 


through  forces  a  little  of  the  solution  up  into  the  bulb-tube,  thus 
prolonging  the  contact.  If  they  are  a  little  too  large,  the  solu- 
tion of  caustic  baryta  may  be  diluted,  after  it  is  measured  in  from 
the  pipette,  with  a  little  distilled  water  to  bring  it  to  the  proper 
Description  volume.  A  is  a  cylinder  containing  oxygen  under  pressure,  or, 

of  the  ap- 
paratus,     if  this  is  not  available,  a  couple  of  bottles  for  forcing  air  through 

the  apparatus  may  be  substituted  (such  as  those  shown  in  Fig. 
57,  page  134).  The  cylinder  and  the  burette  B  are  connected,  as 
shown  in  the  sketch  (Fig.  103),  by  means  of  capillary  tubes  with  the 
bottle  C,  containing  caustic  potassa,  1.27  sp.  gr.  The  bottle  C  is 
connected  with  the  bottle  D,  containing  H2SO4,  and  from  D  a 
capillary  tube  passes  to  the  rubber  stopper  in  the  end  of  the  por- 
Description  celain  tube  EE.  Start  a  current  of  oxygen  or  air  through  the 

of  the 

process.  apparatus  (before  attaching  the  absorption-bottles  G,  G),  light  the 
burners  of  the  furnace,  and  raise  the  temperature  gradually  until 
the  tube  is  red-hot.  Continue  the  passage  of  the  oxygen  until  a 
bottle  containing  a  solution  of  caustic  baryta  attached  to  the  end 
of  the  tube  shows  that  no  CO2  is  given  off.  Measure  out  25  c.c. 
of  the  caustic  baryta  solution  into  each  of  the  bottles  G,  G,  and 
attach  them  as  shown  in  Fig.  103,  open  the  upper  stopcock  of  the 
burette  B,  and  by  means  of  the  3-way  stopcock  let  water  into  the 
burette  from  the  level-tube,  so  that  the  gas  from  the  burette  is 
made  to  bubble  very  slowly  into  the  bottle  C.  About  three  or 
four  bubbles  should  pass  into  C  from  the  oxygen  cylinder  to  one 
from  the  burette.  When  the  water  completely  fills  the  burette 
and  the  capillary  tube  in  C,  close  the  upper  stopcock  of  the 
burette,  and  continue  the  passage  of  the  oxygen  from  A  until  it 
is  certain  that  all  the  gas  has  been  carried  through  the  porcelain 
tube  and  the  absorption-bottles.  In  the  mean  time  measure  out 
25  or  50  c.c.  of  the  caustic  baryta  solution  into  a  porcelain  dish, 
dilute  with  water,  add  a  drop  of  phenolphtalein  solution  (made  by 
dissolving  phenolphtalein  in  alcohol),  and  from  a  burette  run  in 
the  standard  solution  of  oxalic  acid  until  the  pink  color  of  the 
solution  just  vanishes.  This  will  give  the  value  of  the  caustic 


DETERMINATION  OF  NITROGEN.  ^OI 

baryta  solution  in  terms  of  the  normal  oxalic  acid  solution.  When 
the  combustion  is  finished,  detach  the  absorption-bottles,  wash  their 
contents  into  the  dish,  add  a  drop  of  phenolphtalein  solution,  and 
titrate  with  the  oxalic  acid  solution.  The  difference  between  the  calculation 
value  of-  50  c.c.  baryta  solution  and  the  value  of  the  50  c.c.  from  result, 
the  absorption-bottles,  in  terms  of  the  oxalic  acid  solution,  is  the 
number  of  c.c.  of  CH4  in  the  gas  burned  at  760  mm.  barometric 
pressure  and  o°  C.  Divide  this  by  the  number  of  c.c.  burned, 
reduced  to  760  mm.  pressure  and  o°  C.,  multiply  by  100,  and  the 
result  is  the  volume  per  cent,  of  CH4.  Add  together  the  percent- 
ages obtained  of  CO2  (ethylene,  C2H4),  O,  CO,  H,  and  CH4,  sub- 
tract the  sum  from  100,  and  the  remainder  is  the  percentage  of  N  Determina- 

,         j-rr  tionofN. 

by  difference. 

An  example  will  illustrate  the  method  of  analysis,  thus : 


EXAMPLE    OF   ANALYSIS. 

Siemens'  Producer  Gas. 

Volume  of  gas  employed,  99.7  c.c. 

KHO  pipette   ......    93.5  c.c.         Contraction,    6.2  c.c. 

Pyrogallol  pipette    ....    93.3     "  "  0.2    " 

CuCl  "         ....    74.0     "  "  19.3    "    =  19.36 

Transferred  a  portion. 
Remaining  in  pipette   .    .    .    46.8 

Admitted  air  to    .....    98.4 


From  palladium  combustion 


^46.8 
-^ 


CO2 

O 
CO 


=      6.21 
=      0.20 


1.42"    CO  (total)  =  20.78" 

H                 =  11.23" 

CH4            =  3-H" 

N                 =  58.44  " 


Burned  over  palladium  .  .  87.3 
First  contraction  .....  1  1  .  1 
KHO  pipette  ......  86.4 


Second  contraction  ....      0.9     "     =  CO2  =  CO    ,          X  100  =  1.42  <f0   CO. 


H  =  %  [ii.  i]  —  K[°-9]  =  7-i  c.c.     gX  ioo    =  n.23#  H. 

Burned  residue  over  oxide  of  copper  and  absorbed  CO2  in  caustic  baryta  solution. 

Thermometer  17°  C.  Barometer  745  mm.  745«°  —  I4-4=  73O.6 

7  .0086702  X  100     =.86702 
3  .0037158  X     10     =.037158 
o  x       i     =  .000000 

6  .0074316  x      o.i  =  .00074316 

.90492116 
63.24  c.c.  X  .90492116  =  57.23  c.c.  at  760  mm.  and  o°  C. 

50  c.c.  caustic  baryta  solution  =  48.3  c.c.  oxalic  acid 
After  combustion  50  c.c.        "  "  "       =-.  46.5  "          "         " 

Therefore  CH4  in  gas  burned  =    1.8  " 

1.8 
and  5—  X  100  =  3.14  %  CH4. 

302 


TABLES. 


303 


TABLE    I. 

Atomic  Weights  of  the  Elements  used  in  this  Volume. 


Name. 

Symbol. 

At.  Wt. 

Name. 

Symbol. 

At.  Wt. 

Aluminium 

Al 

27  O7 

Manganese 

Mn 

C  C  oo 

Antimony  

Sb 

1  2O.OO 

Molybdenum     

Mo 

JJ-W 
06  oo 

Arsenic                   

As 

yc  oo 

Nickel            ... 

Ni 

cS  7O 

Barium  

Ba 

M7.OO 

N 

14  O7 

Bromine.    ,    

Br 

7Q.QC 

Oxygen  

o 

16  oo 

Calcium 

Ca 

4O  08 

Phosphorus                     . 

p 

-JQ   Q7 

Carbon  

c 

12.  OO 

Pt 

IQ4  8? 

Chlorine     ........ 

Cl 

?C.4C 

Potassium       ...... 

K 

-7Q    II 

Chromium                      . 

Cr 

C2  14 

Silicon 

Si 

28   4O 

Cobalt    

Co 

<»Q.OO 

Na 

21  OS 

CoDoer 

Cu 

67  40 

Sulphur          ...... 

s 

12  06 

H 

I.  OO7 

Tin     

Sn 

IIQ.OO 

Iodine    

I 

126  85 

Titanium    ........ 

Ti 

48  oo 

Iron            . 

Fe 

e6  oo 

Tungsten           

W 

184  oo 

Lead  

Pb 

206.  Qt; 

V 

ci.^7 

Magnesium    

Me 

24  2Q 

Zinc        

Zn 

6c  27 

304 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


TABLE    II. 

Table  of  Factors. 


Found. 


A1P04 Al 

A12O3 Al 

I     Sb.2O4 Sb 

Sb2S3 Sb 

Mg2(NH4)2As2O8-f  H2O As 

Mg2As207 As 

As2S3 As 

As FeAs2 

BaSO4 S 

S03 

CaSO4 CaO 

CaCO3 

CaO CaC03 

!     C02 C 

Cr2O3 Cr 

CoSO4 Co 

CoO 

Co CoO 

CoO Co 

Cu CuO 

Cu2S 

CuO Cu 

Cu2S Cu 

Fe203 Fe 

Fe Fe304 

FeO 

PbSO4 Pb 

PbO 
PbS 


Required. 


Factor. 


O.22l8l 


0.78947 
0.71390 
0.39400 
0.48297 
0.60931 

I-37333 
O.I3756 
0.34352 
0.41193 

0.73513 

1.78459 

0.27273 

0.68479 

0.38050 

0.48370 

1.27119 

0.78667 

1.25240 

1.25284 

0.79849 

0.79818 

0.70000 

1.38095 

1.28571 

0.68298 

0.73578 

0.78879 


Log. 


9.3459811-10 
9.7243168-10 


9.8536374-10 
9.5954962-10 
9.6839202-10 
9.7848383-10 

0.1377749 

9.1384922-10 

9-5359520-10 

9.6148234-10 

9.8663641-10 

0.2515385 

9-4357329-IO 

9-8355574-IO 

9.5803547-10 

9.6845761-10 

0.1042105 

9.8957926-10 

0.0977431 

0.0978956 

9.9022695-10 

9.9021008-10 

9.8450980-10 

0.1401779 

0.1091430 

9.8344080-10 

9.8667480-10 

9.8969614-10 


TABLES. 

TABLE    II.— Continued. 


305 


Found. 


Mg2P207 P 

PA 

MgO 
MgC03 

Mn3O4 Mn 

MnO 

Mn2P2O7 Mn 

MnO 
MnS Mn 

MnO 
(NH4)3nMo03P04 P 

PA 

NiO Ni 

Ni2S Ni 

K2PtCl6 KC1 

K2O 

KC1 ^ .......   i    ....          K2CO3 

Nad .^ Na2O 

Na2C03 

Si02 Si 

S FeS2 

SnO2 Sn 

TiO2 Ti 

V205 V 

W08 W 

ZnO  Zn 


Required. 


Factor. 


0.27836 
0.63788 
0.36212 
0.75760 
0.72052 
0.93013 
0.38741 
0.500II 

0-63I75 
0-81553 
0.01630 

0.03735 
0.78581 
0.78549 
0.30696 

0.19395 
0.92690 

0.53077 

0.90684 
0.47020 
I.87336 
0.78808 
0.60000 
0.56222 
0.79310 
0.80313 


Log. 


9.4446068-10 

9.8047390-10 

9.5588525-10 

9.8794400-10 

9.8576460-10 

9.9685437-10 

9.5881708-10 

9.6990655-10 

9.8005453-10 

9.9114399-10 

8.2121876-10 

8.5722906-10 

9.8953176-10 

9.8951407-10 

9.4870818-10 

9.2876898-10 

9.9670329-10 

9.7249064-10 

9-9575307-IO 

9.6722826-10 

0.2726212 

9.8965703-10 

9.7781513-10 

9.7499063-10 

9.8993279-10 

9.9047858-10 


20 


306 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


TABLE    III. 


Percentages  of  P  and  P2O5  for   each  Milligramme  of  Mg-2P2O7  when   1O 
Grammes  of  the  Sample  are  used. 


Wt.  of 
Mg2P207. 

P. 

P205. 

Wt.  of 
Mg2P207. 

p. 

P205. 

Wt.  of 
Mg2P207. 

P.        P205. 

Wt   of 
Mg2P207. 

P. 

P205. 

I 

0.003 

0.006 

26 

0.073 

o.i  66 

51 

0.142 

0.326 

76 

0.212 

0.486 

2. 

O.OO5 

0.013 

27 

0.075 

0.173 

52 

0.145 

0.332 

77 

0.215 

0.492 

3 

O.OO8 

0.019 

28 

0.078 

0.179 

53 

0.148 

o-339 

78 

0.218 

0.499 

4 

O.OII 

0.026 

29 

0.081 

0.185 

54 

0.151 

o-345 

79 

O.22I 

0.505 

5 

O.OI4 

0.032 

30 

0.084 

0.192 

55 

0.154 

o-352 

80 

O.223 

0.512 

6 

O.OI7 

0.038 

31 

0.086 

0.198 

56 

0.156 

0-358 

81 

0.226 

0.518 

7 

0.019 

0.045 

32 

0.089 

0.204 

57 

0.159 

0.364 

82 

O.229 

0.524 

8 

O.O22 

0.051 

33 

0.092 

O.2II 

58 

0.162 

0.371 

83 

0.232 

0.531 

9 

O.O25 

0.057 

34 

0.095 

0.217 

59 

0.165 

o-377 

84 

0.235      0.537 

10 

O.O28 

0.064 

35 

0.098 

0.224 

60 

0.167 

0.384 

85 

0.237     0-544 

ii 

0.031 

0.070 

36 

O.I  01 

0.230 

61 

0.170 

0.390 

86 

0.240 

0-55° 

12 

°-°33 

0.077 

37 

0.103 

0.237 

62 

0.173 

0.396 

87 

0.243 

o-556 

13 

0.036 

0.083 

38 

0.106 

0.243 

63 

0.176 

0.403 

88 

0.246 

0-563 

14 

0.039 

0.089 

39 

0.109 

0.249 

64 

0.179 

0.409 

89 

0.248 

0.569 

15 

0.042 

0.096 

40 

O.II2 

0.256 

65 

0.181 

0.416 

90 

0.251 

0.576 

16 

0.045 

O.IO2 

4i 

O.II4      O.262 

66 

0.184 

0.422 

9i 

0.254 

0.582 

17 

0.047 

O.IO8 

42 

O.II7 

0.269 

67 

0.187 

0.428 

92 

0.257 

0.588 

18 

0.050 

O.II5 

43 

O.I  2O 

0.275 

68 

0.190 

0-434 

93 

0.259 

o-595 

19 

°-°53 

O.I2I 

44 

0.123 

0.281 

69 

0.193 

0.441 

94 

0.262 

0.601 

20 

21 

0.056 
0.059 

0.128 
0.134 

45 
46 

0.126 

0.128 

0.287 
0.294 

70 
7i 

0.195 
0.198 

0.448 
0-454 

95 
96 

0.265 
0.268 

0.607 
0.614 

22 
23 

0.061 
0.064 

O.I4I 
0.147 

47 
48 

0.131 
0.134 

0.300 
0.307 

72 
73 

0.201 

0.2O4 

0.460 
0.467 

97 
98 

0.271 

0.274 

0.620 
0.627  ' 

24 

0.067 

0-153 

49 

0.137 

0-3I3 

74 

0.2O7 

0-473 

99 

0.276 

0-633 

25 

0.070 

O.I59 

50 

0.139 

0.319  j 

75 

O.2O9 

0-479 

100 

0.278 

0.638 

TABLES. 


307 


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308 


7 HE   CHEMICAL   ANALYSIS    OF  IRON. 


TABLE    V. 

Table  for  Reducing  Volumes  of  Gases  to  the  Normal  State. 
BY    PROFESSOR   DR.    LEO   LIEBERMANN. 

(From  Winkler's  "Technical  Gas  Analysis.") 

Instructions  for   Use. 

Suppose  the  volume  of  a  gas  to  have  been  found  =26.2  c.c.  at  742  mm.  barometric  pressure, 
1 8°  C.  temperature,  saturated  with  moisture.  In  order  to  reduce  it  to  the  normal  state  (760  mm., 
o°  C.,  dry),  we  proceed  as  follows: 

1st.  Look  out  the  degree  18  (columns  I  and  4),  and  deduct  the  tension  of  aqueous  vapor  given, 
=  15.3  mm.,  from  the  observed  pressure,  =  742.0: 

742.0—15.3  =  726.7  mm. 

2d.  Now  find  the  volume  which  I  vol.  of  the  gas  would  have  at  the  pressure  of  726.7  mm. 
by  looking  out  seriatim  the  figures  7,  2,  6,  and  7  in  column  2  at  the  temperature  1 8°,  and  placing 
the  numerical  values,  to  be  found  opposite  those  figures,  in  the  same  column,  multiplying  them 
seriatim  by  100,  10,  i,  o.i  ;  whereupon  they  are  added  up,  thus: 

0.0086408  X  IO°     =0.86408 
0.0024688%     Io     =0.024688 


7 

2 

6  0.0074064  X 

7  0.0085408  X 


i  =  0.0074064 
o.  i  =  0.00086408 


0.89703848 

3d.  The  corrected  volume  of  a  cubic  centimetre  is  lastly  multiplied  by  the  number  of  the  c.c. 
previously  found ;    that  is,  in  the  present  case, 

0.89703848X26.2  =  23.502  c.c. 


Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq.  ! 
vapor  in  millim.  i 
of  mercury 
for  °  C. 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

O 

I 

0.0013157 

O 

6 

0.0078946 

O 

2 

0.0026315 

O 

7 

O.OO92IO4 

O 

3 

0.0039473 

O 

8 

0.0105262 

O 

4 

0.0052631 

O 

9 

O.OII842O 

O 

5 

0.0065789 

o°  =  4-5 

TABLES. 

TABLE  V. — Continued. 


309 


Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

I 

I 

0.0013109 

4 

! 

0.0012965 

I 

2 

0.0026219 

4 

2 

0.0025930 

I 

3 

0.0039328 

4 

3 

0.0038895 

I 

4 

0.0052438 

4 

4 

0.0051860 

I 

5 

0.0065548 

I°  =  4.9 

4 

5 

0.0064825 

4°  ==  6.0 

I 

6 

0.0078657 

4 

6 

0.0077790 

I 

7 

0.0091767 

4 

7 

0.0090755 

I 

8 

0.0104876 

4 

8 

O.OIO372O 

I 

9 

0.0117986 

4 

9 

0.0116685 

2 

i 

0.0013061 

5 

i 

0.0012916 

2 

2 

0.0026123 

5 

2 

0.0025833 

2 

3 

0.0039184 

5 

3 

0.0038750 

2 

4 

0.0052246 

5 

4 

0.0051667 

2 

5 

0.0065307 

2°  =  5-2 

5 

5 

0.0064584 

5°  =  6.5 

2 

6 

0.0078369 

5 

6 

0.007750! 

2 

7 

0.0091430 

5 

7 

0.0090418 

2 

8 

0.0104492 

5 

8 

0-0103335 

2 

9 

0-0"7553 

5 

9 

0.0116252 

3 

i 

0.0013013 

6 

i 

0.0012868 

3  - 

2 

0.0026026 

6 

2 

0.0025737 

3 

3 

0.0039039 

6 

3 

0.0038606 

3 

4 

0.0052053 

6 

4 

0.0051474 

3 

5 

0.0065066 

3°  =  5-6 

6 

5 

0.0064343 

6°  ==  6.9 

3 

6 

0.0078079 

6 

6 

0.0077212 

3 

7 

0.0091093 

6 

7 

0.0090080 

3 

8 

O.OIO4IO6 

6 

8 

0.0102949 

3 

9 

0.0117119 

6 

9 

0.0145818 

3io 


THE    CHEMICAL    ANALYSIS   OF  IRON. 

TABLE  V.— Continued. 


Tempera- 
ture  o  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

7 

I 

0.0012828 

10 

I 

0.0012692 

7 

2 

0.0025656 

10 

2 

0.0025384 

7 

3 

0.0038484 

10 

3 

0.0038076 

7 

4 

0.0051312 

IO 

4 

0.0050768 

7 

5 

0.0064140 

7°  =  7-4 

IO 

5 

0.0063460 

10°  =  9.1 

7 

6 

0.0076968 

IO 

6 

0.0076152 

7 

7 

0.0089796 

10 

7 

0.0088844 

7 

8 

0.0102624 

IO 

8 

0.0101536 

7 

9 

0.0115452 

IO 

9 

0.0114228 

8 

i 

0.0012783 

II 

i 

0.0012648 

8 

2 

0.0025566 

II 

2 

0.0025296 

8 

3 

0.0038349 

II 

3 

0.0037944 

8 

4 

0.0051132 

II 

4 

0.0050592 

8 

5 

0.0063915 

8°  =  8.0 

II 

5 

0.0063240 

11°  =  9.7 

8 

6 

0.0076698 

II 

6 

0.0075888 

8 

7 

0.0089481 

II 

7 

0.0088536 

8 

8 

0.0102264 

II 

8 

O.OIOII84 

8 

9 

0.0115047 

II 

9 

0.0113832 

9 

i 

0.0012737 

12 

i 

0.0012603 

9 

2 

0.0025474 

12 

2 

O.OO252O6 

9 

3 

0.0038211 

12 

3 

0.0037809 

9 

4 

0.0050948 

12 

4 

0.0050412 

9 

5 

0.0063685 

9°  =  8.5 

12 

5 

0.0063015 

12°  =  IO.4 

9 

6 

0.0076422 

12 

6 

0.0075618 

9 

7 

0.0089159 

12 

7 

O.OO8822I 

9 

8 

0.0101896 

12 

8 

O.OIOO824 

9 

9 

0.0114633 

12 

9 

0.0113427 

| 

TABLES. 


TABLE  V.—  Continued. 


Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  o  C. 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  o  C. 

J3 

I 

0.0012559 

16 

I 

O.OOI2429 

J3 

2 

0.0025II8 

16 

2 

0.0024858 

13 

3 

0.0037677 

16 

3 

0.0037287 

13 

4 

0.0050236 

16 

4 

0.0049716 

J3 

5 

0.0062795 

13°  =  11.  1 

16 

5 

0.0062145 

16°  =  13.5 

13 

6 

°-0°75354 

16 

6 

0.0074574 

13 

7 

0.0087913 

16 

7 

0.0087003 

13 

8 

0.0100472 

16 

8 

0.0099432 

J3 

9 

0.0113031 

16 

9 

o.oi  11861 

H 

i 

0.0012516 

17 

i 

0.0012,386 

H 

2 

0.0025032 

17 

2 

0.0024772 

H 

3 

0.0037548 

17 

3 

0.0037158 

H 

4 

0.0050064 

17 

4 

0.0049544 

H 

5 

0.0062580 

14°  =  11.9 

17 

5 

0.0061930 

1  7°  =  14.4 

H 

6 

,0.0075096 

17 

6 

O.OO743I6 

H 

7 

0.0087612 

17 

7 

O.OO867O2 

H 

8 

0.0100128 

17 

8 

0.0099088 

14 

9 

0.0112644 

17 

9 

O.OIII474 

15 

i 

0.0012472 

18 

i 

0.0012344 

15 

2 

0.0024944 

18 

2 

0.0024688 

15 

3 

0.0037416 

18 

3 

0.0037032 

15 

4 

0.0049888 

18 

4 

0.0049376 

15 

5 

0.0062360 

15°  =  12.7 

18 

5 

O.OO6I72O 

180  =  15.3 

15 

6 

0.0074832 

18 

6 

0.0074064 

i5 

7 

0.0087304 

18 

7 

0.0086408 

15 

8 

0.0099776 

18 

8 

0.0098752 

15 

9 

0.0112248 

18 

9 

O.OIII096 

312 


THE    CHEMICAL   ANALYSIS   OF  IRON. 


TABLE  V.— Continued. 


r 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

| 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

Tempera- 
ture °  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

19 

I 

O.OOI23OI 

22 

I 

O.OOI2I76 

19 

2 

0.0024602 

22 

2 

0.0024352 

J9 

3 

0.0036903 

22 

3 

0.0036528 

J9 

4 

0.0049204 

22 

4 

0.0048704 

19 

5 

0.0061505 

I9°  =  I6.3 

22 

5 

0.006o88o 

22°  =  19.6 

19 

6 

0.0073806 

22 

6  ' 

0.0073056 

J9 

7 

O.OO86lO7 

22 

7 

0.0085232 

J9 

8 

0.0098408 

22 

8 

0.0097408 

19 

9 

O.OII0709 

22 

9 

0.0109584 

20 

i 

O.OOI2259 

23 

i 

O.OOI-2I35 

20 

2 

0.0024518 

23 

2 

0.0024270 

20 

3 

0.0036777 

23 

3 

0.0036405 

20 

4 

0.0049036 

23 

4 

0.0048540 

20 

5 

0.0061295 

2O°  =  17.4 

23 

5 

0.0060675 

23°  =  2O.9 

20 

6 

0-0073554 

23 

6 

0.0072810 

20 

7 

0.0085813 

23 

7 

0.0084945 

20 

8 

0.0098122 

23 

8 

0.0097080 

20 

9 

O.OIIO33I 

23 

9 

0.0109215 

21 

i 

0.0012218 

24 

i 

O.OOI2O94 

21 

2 

0.0024436 

24 

2 

0.0024188 

21 

3 

0.0036654 

24 

3 

0.0036282 

21 

4 

0.0048872 

24 

4 

0.0048376 

21 

5 

0.0061090 

21°  =18.5 

24 

5 

0.0060470 

24°  =  22.2 

21 

6 

0.0073308 

24 

6 

0.0072564 

21 

7 

0.0085526 

24 

7 

0.0084658 

21 

8 

0.0097744 

24 

8 

0.0096752 

21 

9 

0.0109962 

24 

9 

0.0108846 

TABLES. 

TABLE  V.— Continued. 


313 


Tempera- 
ture o  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

Tempera- 
ture o  C. 

Pressure 
in  millims. 
mercury. 

Volume  at  o° 
and  760  mm. 

Tension  of  aq. 
vapor  in  millim. 
of  mercury 
for  °  C. 

25 

I 

O.OOI2O54 

28 

I 

0.0011933 

25 

2 

0.0024108 

28 

2 

0.0023866 

25 

3 

0.0036162 

28 

3 

0.0035799 

25 

4 

0.0048216 

28 

4 

0.0047732 

25 

5 

0.0060270 

25°  =  23.5 

28 

5 

0.0059665 

28°  =  28.  1 

25 

6 

0.0072324 

28 

6 

0.0071598 

25 

7 

0.0084378 

28 

7 

0.0083531 

25 

8 

0.0096432 

28 

8 

0.0095464 

25 

9 

0.0108486 

28 

9 

0.0107397 

26 

i 

O.OOI20I3 

29 

i 

0.0011894 

26 

2 

O.OO24O26 

29 

2 

0.0023788 

26 

3 

0.0036039 

29 

3 

0.0035682 

26 

4 

0.0048052 

29 

4 

0.0047576 

26 

5 

0.0060065 

26°  =r  25.0 

29 

5 

0.0059470 

29°  =  29.8 

26 

6 

0.0072078 

29 

6 

0.0071364 

26 

7 

0.0084091 

29 

7 

0.0083258 

26 

8 

0.0096104 

29 

8 

0.0095152 

26 

9 

O.OI08II7 

29 

9 

0.0107046 

27 

i 

0.0011973 

3° 

i 

O.OOII855 

27 

2 

0.0023946 

30 

2 

0.0023710 

27 

3 

0.0035919 

30 

3 

0.0035565 

27 

4 

0.0047892 

30 

4 

0.0047420 

27 

5 

0.0059865 

270  =  26.5 

30 

5 

0.0059275 

30°  =  31.6 

27 

6 

0.0071838 

30 

6 

0.0071130 

27 

7 

0.0083811 

30 

7 

0.0082985 

27 

8 

0.0095784 

30 

8 

0.0094840 

27 

9 

0.0107757 

30 

9 

0.0106695 

APPENDIX. 


Determination  of  Nickel  and  Aluminium  in  Steel. 

AN  admirable  and  rapid  method  for  the  determination  of  nickel  or 
aluminium  in  steel  has  been  worked  out  by  Mr.  George  H.  Chase  of  the 
Midvale  Steel  Company,  Philadelphia,  from  the  separation  mentioned  by 
J.  W.  Rothe.*  This  is  based  on  the  fact  that  ether  will  take  ferric  chloride 
from  its  solution  in  dilute  hydrochloric  acid,  leaving  aluminium,  nickel, 
and  copper  chlorides  in  the  hydrochloric  acid  solution. 

The  details  as  communicated  to  me  by  Mr.  Chase  are  as  follows : 

Determination  of  Nickel, 

Dissolve  2  grammes  of  steel  in  dilute  hydrochloric  acid  (i.i  sp.  gr.), 
add  sufficient  nitric  acid  to  oxidize  the  iron,  and  evaporate  to  dryness. 
Redissolve  in  hydrochloric  acid  and  evaporate  until  ferric  chloride  begins 
to  separate.  Add  hydrochloric  acid,  i.i  sp.  gr.,  to  redissolve  any  basic 
salt,  and  transfer  the  solution  to  a  250  c.c.  separatory  funnel  provided  with 
a  glass  stop-cock  and  closed  at  the  top  with  a  ground  glass  stopper. 

As  hydrochloric  acid  of  i.i  sp.  gr.  only  is  used  in  this  method  it  is 
best  to  have  a  wash-bottle  filled  with  it.  Wash  the  solution  out  of  the 
beaker  with  hydrochloric  acid,  being  careful  that  the  entire  volume  of  solu- 
tion and  washings  in  the  funnel  shall  not  exceed  50  c.c.  Pour  40  c.c.  of 
C.  P.  ether  into  the  funnel,  insert  the  glass  stopper,  and  shake  vigorously 
for  eight  minutes.  The  ether  gradually  removes  the  ferric  chloride  from 
the  solution  and  finally  appears  as  an  emerald-green  solution  floating  on 
top  of  the  aqueous  solution  of  the  other  chlorides.  Allow  the  funnel  to 
stand  for  a  few  minutes  and  then  run  the  lower  solution  which  contains 
the  nickel,  copper,  and  aluminium  chlorides  into  another  similar  separatory 
funnel  into  which  40  c.c.  of  ether  has  been  previously  placed.  Close  the 
stop-cock  and  wash  the  glass  stopper  with  a  little  hydrochloric  acid,  allow- 
ing it  to  run  into  the  first  funnel,  and  wash  the  funnel  itself  with  a  little 

*  Miltheilungen  aus  den  Koniglich.  Tech.  Versachs  anstalten  zu  Berlin,  1892,  part  iii. 


APPENDIX. 

more  acid.  Allow  this  to  run  into  the  second  funnel  and  repeat  the  wash- 
ing. When  the  second  washing  has  run  into  the  second  funnel  pour  the 
green  etherial  solution  into  a  bottle  and  reserve  it  to  distil  and  recover  the 
ether.  Shake  the  second  funnel  for  eight  or  ten  minutes  to  remove  the 
last  of  the  ferric  chloride  and  separate  and  wash  as  before.  Boil  the  sepa- 
rated liquid  which  contains  the  nickel,  copper,  and  aluminium  chlorides,  and 
the  hydrochloric  acid  to  expel  a  trace  of  ether,  add  an  excess  of  ammonia 
to  precipitate  any  iron  or  alumina  that  may  be  present  and  boil.  Filter, 
wash,  redissolve  in  hydrochloric  acid,  reprecipitate  by  ammonia,  and  filter. 
Add  the  two  filtrates  together,  acidulate  strongly  with  hydrochloric  acid, 
and  pass  sulphuretted  hydrogen  to  get  rid  of  the  copper.  Filter,  nearly 
neutralize  the  filtrate  with  ammonia,  add  5  to  10  grammes  of  ammonium 
or  sodium  acetate,  and  precipitate  the  nickel  by  sulphuretted  hydrogen. 
Determine  the  nickel  as  directed  on  page  1 86.  Or  evaporate  the  liquid 
separated  from  the  etherial  solutions  to  low  bulk,  separate  the  copper  by 
sulphuretted  hydrogen,  evaporate  the  nickel  solution  with  an  excess  of 
sulphuric  acid,  and  separate  the  nickel  by  the  battery. 

Mr.  Chase  prefers  to  run  the  liquid  from  the  second  treatment  with 
ether  into  5  to  10  grammes  of  ammonium  chloride  dissolved  in  100  c.c. 
strong  ammonia,  and  after  heating  to  boiling  to  filter  off  the  precipitated 
ferric  hydrate,  then  to  boil  off  all  the  ammonia,  filter  if  necessary,  add 
10  grammes  of  sodium  or  ammonium  acetate,  and  precipitate  the  nickel 
by  sulphuretted  hydrogen  at  a  temperature  of  about  80°  C.  He  sub- 
tracts the  cuprous  sulphide,  previously  determined,  from  the  sulphides 
thus  obtained. 

A  determination  of  nickel  can  be  made  by  this  method  in  about  two 
hours,  and  the  results  are  very  accurate. 

Determination  of  Aluminium. 

Proceed  as  in  the  determination  of  nickel  until  the  liquid  from  the 
treatments  with  ether  is  obtained.  Evaporate  to  dryness,  redissolve  in  a 
little  hydrochloric  acid,  filter,  add  sodium  ammonium  phosphate  and 
sodium  hyposulphite,  and  precipitate  by  sodium  acetate,  determining  the 
aluminium  as  on  page  192. 


INDEX. 


Absorption   apparatus    for  CO2  in   carbon 

determinations 145 

precautions  in  weighing    ....  146 

Acetic  acid,  reagent 40 

Acids  and  halogens 38 

Air,  compressed,  for  use  in  carbon  deter- 
mination in  iron  and  steel     156 

Air-bath 19 

Air-blast  with  Richards's  injector    ....  23 

Alkalies,  determination  of,  in  clay  .    .    272,  273 

determination  of,  in  iron  ores  ....  255 

Alkaline  earths,  salts  of 50 

salts 44 

Allen,  determination  of  nitrogen  in  iron 

and  steel ....  2OI 

Alumina  and  ferric  oxide,  separation  of     .  248 

by  caustic  potassa  or  soda    .    .    .  249 

by  hyposulphite  of  sodium  .    .    .  250 

by  sulphide  of  ammonium    .    .    .  248 
by  volatilization  of  the  iron  in  a 
current  of  HC1  after  reduction 

by  H 250 

Aluminium,     separation     of,    from    chro- 
mium       188, 189 

Aluminium  and  chromium,  determination 

of,  in  iron  and  steel 187,  191,  192 

Ammonia,  jeagent 44 

Ammonium,  acetate  of,  reagent 45 

bisulphite  of,  reagent 44 

chloride  of,  reagent 45 

fluoride  of,  reagent 45 

nitrate  of,  reagent 45 

oxalate  of,  reagent 45 

salts,  decomposition  of,  by  HNO3    .    .  256 

sulphide  of,  reagent 44 

Antimony,  determination   of,  in  iron  and 

steel 196 


Apparatus 1 1 

general  laboratory 19 

Arsenic,  determination  of,  as  As2S8     ...  196 

as  Mg2As2O7 196 

by  distillation 195 

in  iron  and  steel 195 

Arsenic  and  antimony,  separation  of,  from 

copper  and  lead 253 

Arsenic,  copper,  antimony,  and  lead,  deter- 
mination of,  in  iron  ores 253 

Asbestos  stoppers 144 

Babbitt,  use  of  red  lead  in  Deshays's  method 
for  determination  of  manganese  in  iron 

and  steel 125 

Balances 36 

Barba,  asbestos  for  settling  carbonaceous 

matter  in  solutions  of  steel  .    .    .    .  151 

determination  of  chromium  in  steel    .  194 

member  of  sub  committee  on  methods  95 

Barium,  acetate  of,  reagent 51 

carbonate  of,  reagent 50 

chloride  of,  reagent 51 

hydrate  of,  reagent 51 

Baryta,  caustic,  reagent 51 

caustic,  standard  solution  of,  for  de- 
termination of  methane 299 

Berzelius,  determination  of  carbon  in  iron 

and  steel 129,  130 

determination  of  sulphur  in  iron  and 

steel     .    ,. 62 

Binks,  determination  of  carbon  in  iron  and 

steel 130 

Boat  of  platinum-foil  for  determination  of 

carbon  in  iron  and  steel 159 

Britton,  permanent  standards  for  color-car- 
bon method 174 

3'5 


INDEX. 


Bromine,  reagent 41 

Bromine-water  for  absorbing  ethylene   .    .  293 

Bunsen  burners      22 

chimneys  for 22 

Bunsen,  determination  of  MnO2  in   iron 

ores 235 

Bunsen's  method  of  rapid  filtration    ...  24 

Burette,  form  of,  without  glass  stopcock    .  213 

Jones's 211 

Calcium,  carbonate  of,  reagent 52 

chloride  of,  reagent 52 

Camera,  for  use  in  color-carbon  method    .     173 

Caps  for  reagent  bottles 32 

Carbon,  determination  of,  in  iron  and  steel    129 
in  carbonaceous  matter,  determination 

of,  in  iron  ores 259 

Carbon,  combined,  determination  of,  in  iron 

and  steel  by  color  method    .    .     167 
determination    of,  in  white    cast 

iron  and  pig-iron   ....     176 

by  direct  method 167 

by  indirect  method    ....     167 
limitations  of  color  method     .    .     167 
Carbon,  total,  determination  of,  in  iron  and 

steel 129 

by  combustion  with  chromate  of 

lead  and  chlorate  of  potassium     132 
by  combustion  with  oxide  of  cop- 
per in  a  current  of  oxygen  .    .     135 
by  combustion  with  potassium  bi- 

sulphate 135 

by  direct  combustion  in  a  current 

of  oxygen 131 

by  solution  and  oxidation  of  the 
borings  by  sulphuric,  chromic, 
and  phosphoric  acids,  the  vol- 
ume of  CO2  being  measured  .  136 
by  solution  and  oxidation  of  the 
borings  by  sulphuric,  chromic, 
and  phosphoric  acids,  the  CO2 

being  weighed 140 

by  solution  in  chloride  of  copper, 

and  combustion  of  residue   .    .     162 
by  solution  in  double  chloride  of 
copper    and    ammonium,    and 
weighing  or  combustion  of  res- 
idue  148 


Carbon,  total,  determination  of,  by  solution 
in  chloride  of  copper  and  chlo- 
ride of  potassium,  and  combus- 
tion of  residue 161 

by  solution  in  dilute  hydrochloric 
acid  in  an  electric  current,  and 
combustion  of  residue  ....     165 
by  solution  in  iodine  or  bromine, 

and  combustion  of  residue  .    .     162 
by  solution  on  fused  chloride  of  ? 
silver,  and  combustion  of  resi- 
due   163 

by  solution  in  sulphate  of  copper, 
and  combustion  of  residue  by 

CrO3  and  H2SO4 164 

by  solution  in  sulphate  of  copper, 
and  combustion  of  residue  in  a 

current  of  oxygen 163 

by  volatilization  in  a  current  of  Cl, 

and  combustion  of  residue  .    .     142 
by  volatilization  in  a  current  of 
HC1,  and  combustion  of  resi- 
due   148 

Carbonic  acid  gas,  absorbent  for  ....  291 
apparatus  for  generating  ....  42 
determination  of,  in  gases  .  .  .  295 
determination  of,  in  iron  ores  .  .  257 
purifying  and  drying  apparatus 
for,  in  carbon  determinations  . 

144,  154,  156 

Carbonic  oxide  gas,  absorbent  for  .    .    .    .     291 
absorption  of,  by  cuprous  chloride    293 
determination  of,  in  gases    .    .    .     296 
Carnot,  determination  of  aluminium  in  iron 

and  steel 192 

Chimneys  for  Bunsen  burners 22 

Chlorine,  reagent 41 

Chrome  iron  ore,  analysis  of 263 

Chromium,  determination  of,  in  iron  and 

steel 190 

determination  of,  in  iron  ores  ....  262 
separation  of,  from  aluminium  .  188,  189 
volumetric  method  for  determination 

of,  in  iron  and  steel 193 

Chromium  and  aluminium,  determination 

of,  in  iron  and  steel 187 

separation  of,  from  P2O5   ....     189 
Cinder,  mill  and  tap,  analysis  of     ....    278 


INDEX. 


317 


Citric  acid,  reagent 40 

Clay,  methods  for  the  analysis  of    ....  271 

Coal,  analysis  of  the  ash  of 283 

determination  of  sulphur  in     ....  284 

proximate  analysis  of 282 

Coal  and-coke,  methods  for  the  analysis  of  282 

Cobalt,  determination  of,  as  CoSO4     .    .  185 

determination  of,  by  electrolysis  ...  1 86 
Cobalt  and  nickel,  determination  of,  in  iron 

and  steel 184 

Coke,  determination  of  sulphur  in  ....  284 
Combined  water,  determination  of,  in  iron 

ores 259 

Comparison-tubes  for  color  carbon  method  172 

Cone,  Gooch's  perforated 27 

Copper,  determination  of,  as  CuO   ....  184 

as  Cu2S 183 

by  electrolysis 182 

by  precipitation  by  hyposulphite 

of  sodium 183 

anhydrous  sulphate  of,  reagent    ...  53 

metallic,  reagent 52 

oxide  of,  reagent 54 

sulphate  of,  reagent 53 

Copper  and  ammonium,  double  chloride  of, 

reagent 54 

and  potassium,  double  chloride  of,  re- 
agent     54 

lead,  arsenic,  and  antimony,  determina- 
tion of,  in  iron  ores 253 

Counterpoised  filters 27 

Craig,  determination  of  sulphur  in  iron  and 

steel 65 

Crucible,  Gooch's  perforated 26 

platinum 32 

Crucible-tongs,  forms  of 35 

Cupric  chloride,  reagent 53 

Cuprous  chloride,  anhydrous,  reagent     .    .  53 
for   absorbing   carbon   monoxide 

291,  293 

Deshays,  determination  of  manganese  in 

iron  and  steel 124 

Desiccators 32 

Deville,  determination  of  carbon  in  iron 

and  steel 130 

Dexter,  method  of  separation  for  Cr  and  Al  188 

Dishes,  platinum 34 


Distilled  water 37 

apparatus  for  making 38 

Drill-press 15 

Drill-press  for  holding  half  pig  of  iron  .    .  15 

Drill-press  and  balance 16 

Drown,  determination  of  silicon    in   iron 

and  steel 73 

determination  of  sulphur  in  iron  and 

steel 64 

determination  of  titanium  in  iron    .    .  180 
member  of  sub-committee  on  standard 

methods 95 

Drying  and  purifying  apparatus  for  CO2  in 

carbon  determinations  ....     144,  154,  156 
Dubois,  Mixer  and,  determination  of  iron 

in  iron  ores 218 

Dudley,  chairman  sub- committee  on  stand- 
ard methods 95 

Eggertz,  determination  of  carbon  in  iron 

and  steel 130 

determination  of  combined  carbon  in 

iron  and  steel 167 

determination  of  phosphorus  in  iron 

and  steel 92 

Elliott,  determination  of   sulphur  in  iron 

and  steel 68 

Eschka,  determination  of  sulphur  in  coal 

and  coke 285 

Ethylene,  absorbent  for 293 

determination  of,  in  gases 295 

Factor  weights 37 

Feather  for  removing  precipitates    ....  31 
Ferric  chloride,  solution  of,  for  standard- 
izing solutions  of  permanganate  and  bi- 
chromate       219 

Ferrous  oxide,  determination  of,  in  iron  ores  223 

sulphate,  reagent 55 

Filters,  apparatus  for  washing  ." 29 

ashless 29 

Filtering-tubes  for  carbon  determinations  in 

iron  and  steel 157 

Filter-paper 28 

Filter-pumps 23 

Filtration,  Bunsen's  method  of 24 

Fire-sand,  methods  for  analysis  of  .    .    .    .  281 


INDEX. 


Forceps  for  use  in  carbon  determinations  in 

iron  and  steel 154 

Ford,  determination  of  manganese  in  iron 

and  steel 115 

rapid  method  for  determination  of  sili- 
con in  pig-iron 77 

Fresenius,  determination  of  phosphorus  in 

iron  and  steel      81 

determination  of  sulphur  in  iron  and 

steel 63 

Galbraith,  volumetric  method  for  determi- 
nation of  chromium  in  iron  and  steel  .    .  193 
Gas,  heating,  composition  of 291 

Siemens's  producer,  example  of  analy- 
sis of   302 

Gases,  analysis  of,  by  Hempel's  apparatus  293 

collecting  samples  of,  for  analysis    .    .  288 

methods  for  the  analysis  of 288 

reagents 42 

Genth,  method  of  decomposing  chrome  ores  263 

method  for  the  separation  of  Al  and  Cr  189 
Glass  filtering-tube  for  carbon  determina- 
tions in  iron  and  steel 157 

Gooch,  separation  of  TiO2  and  A12O3     .    .  231 

Gooch's  method  of  filtration 26 

perforated  crucible  and  cone    ....  26 
Graphitic  carbon,  determination  of,  in  iron 

and  steel 166 

Hempel's   apparatus   for    the   analysis    of 

gases 288 

Hogarth,  specific-gravity  flask 265 

Hydrochloric  acid,  reagent 38 

Hydrofluoric  acid,  apparatus  for  distilling  39 

reagent 39 

Hydrogen,  combustion  of,  with  spongy  pal- 
ladium       297 

gas,  apparatus  for  generating   ....  43 
Hydroscopic   water,  determination   of,   in 

iron  ores 206 

Igniting  precipitates 22 

Insoluble  silicious  matter  in  iron  ores,  anal- 
ysis of ...  239 

Iodine,  reagent 41 

Iron,  determination  of  metallic,  in  iron  and 

steel 204 

Iron,  total,  determination  of,  in  iron  ores    .  207 


Iron,  total,  in  irqn  ores,  determination  of,  by 

deoxidation  by  NH4HSO3  216 
by  deoxidation  by  SnCLj    .    .  217 
by  deoxidation  by  Zn    .    .    .  208 
by  standard  solution  of  bi- 
chromate of  potassium  .    .  215 
by  standard  solution  of  per- 
manganate of  potassium  .  209 

Iron  ores,  method  of  sampling 205 

Iron  wire,  reagent 55 

Iron  and  ammonium,  double  sulphate  of, 

reagent 55 

Jones's  reductor 209 

Karsten,  determination  of  graphitic  carbon 

in  iron  and  s*teel 166 

determination  of  sulphur  in  iron  and 

steel 59 

Kudernatsch,  determination  of  carbon  in 

iron  and  steel 130 

Langley,  determination  of  carbon  in  iron 

and  steel 130 

determination  of  nitrogen  in  iron  and 

steel 201 

Lead,  determination  of,  as  PbSO4  in  iron 

ores      253 

chromate  of,  reagent 56 

oxide  of,  dissolved  in  caustic  potassa  .  57 

peroxide  of,  reagent 57 

Lead,  copper,  arsenic,  and  antimony,  deter- 
mination of,  in  iron  ores 253 

Limestone,  methods  for  the  analysis  of  .    .  267 

occasional  constituents  of 268 

Lundin,  determination  of  arsenic  in  iron 

and  steel 195 

Magnesia  mixture,  reagent 58 

Manganese,  binoxide  of,  in  iron  ores  .    .    .  235 
determination    of,    by     Bunsen's 

method 236 

by  ferrous  sulphate  method  .  237 

determination  of,  as  Mn3O4 113 

as  MnS 114 

as  Mn2P2O7 112 

in    iron    and    steel,    by    acetate 

method 109 


INDEX. 


319 


Manganese,  determination  of,  in  iron  and 

steel,  by  Deshays's  method  .    .  124 

by  Ford's  method 115 

by  HNO3  and  KC1O3  method     .  115 

by  Volhard's  method 118 

by  Williams' s  method   .....  1 20 
in     presence    of    much     silicon 

(Wood's  method) 117 

rapid  methods 118 

remarks   on  the  use   of    acetate 

method H4 

in  iron  ores 233 

by  Volhard's  method 234 

by  Pattinson's  method 234 

in  pig-iron,  spiegel,  and  ferro-manga- 

nese,  by  Ford's  method 118 

in  spiegel  and  ferro-manganese    ...  123 

by  Pattinson's  method 125 

by  Williams' s  method 123 

determination  of,  in  steel,  by  the  color 

method 126 

in  presence  of  much  silicon  (by  Ford's 

method) ,    .' 117 

Marguerite's  method  for  determination  of 

iron 209 

Matthewman,  determination  of  sulphur  in 

pig-iron 66 

McCreath,  determination  of  carbon  in  iron 

and  steel     .    .    .    .  - 130 

Measuring-glasses  for  reagents 31 

Mercuric  oxide,  reagent 56 

Mercurous  nitrate,  reagent      56 

Metals  and  metallic  salts,  reagents  ....  52 
Methane,  determination  of,  in  gases    .    .    .  298 
Microcosmic  salt,  quantity  in  the  determi- 
mination    of    MgO    in     lime- 
stones    268 

reagent 46 

Mixer  and  Dubois,  determination  of  iron  in 

iron  ores 218 

Molybdate  solution,  reagent 58,  99 

Morrell,  determination  of  sulphur  in  iron 

and  steel 62 

Mortar,  agate,  with  Stow  flexible  shaft  .    .  13 
agate,  White's    arrangement    to    use 

with  power 14 

hardened  steel,  for  spiegel 17 

Mortar  and  pestle,  steel,  for  crushing  ores  12 


Nichols,  details  of  rapid  method  for  deter- 
mination of  phosphorus  in  iron  and  steel  108 
Nickel,  determination  of,  as  Ni2S  or  NiO  .  186 

separation  of,  from  cobalt 185 

Nickel    and   cobalt,  determination  of,  by 

electrolysis 186 

determination  of,  in  iron  and  steel  184 
separation  of,  from  copper    ...  184 
Nickel,  cobalt,  zinc,  and  manganese,  deter- 
mination of,  in  iron  ores 251 

Nickel  steel,  analysis  of 186 

Nitric  acid,  reagent       39 

Nitrogen,   determination   of,   in  iron  and 

steel 201 

Oxalate  of  ammonium,  quantity  required 
in  the  determination  of  CaO  in  lime- 
stones    267 

Oxalic  acid,  reagent 40 

standard  solution  of,  for  determi- 
nation of  methane 299 

Oxide  of  copper  plugs,  preparation  of   .    .  142 

Oxygen,  determination  of,  in  gases     .    .    .  296 

gas,  absorbent  for 291 

reagent 43 

Pan,  aluminium,  for  weighing  samples  .    .      36 
Pearse,  determination  of  carbon  in  iron  and 

steel 130 

Penny's  method  for  determination  of  iron  .    215 
Perforated  boat   and  holder   for  filtering 
carbonaceous   residues    from    iron    and 

steel 151,  152 

Permanent  standards  for  color  carbon  de- 
termination   174 

Permanganate     of     potassium      solution, 

methods  of  standardizing      218-222 
standard  solution  of,  for  determi- 
nation of  iron 209 

Peters,  determination  of  manganese  in  steel 

by  color  method 126 

Phillips,  determination  of  sulphur  in  pig- 
iron  66 

Phosphoric  acid,  determination  of,  in  coal 

and  coke 286 

in  iron  ores 229 

in  limestone 269 

in  slags 279 


320 


INDEX. 


Phosphorus,  determination  of,  in  iron  and 

steel 81 

by  direct  weighing  of  phospho- 

molybdate 1 08 

by  the  acetate  method  ....  81 
by  the  acetate  method,  precau- 
tions necessary 84 

by  the  combination  method  .    .  93 
by  the  molybdate  method     .    .  89 
by  the  molybdate  method,  pre- 
cautions necessary      ....  92 
by  volumetric  method  (method 
of     the     sub-committee     on 
methods  of  the  International 
Steel  Standards  Committee)  95 
by  rapid  methods  .    .        .        -95 
when  titanium  is  present  86,  94 

asMg2P207 85 

as  Mg2P2O7  with  previous  pre- 
cipitation as  phospho-molyb- 

date 91 

as  phospho-molybdate  of  am- 
monium    92 

separation  of,  from  arsenic  ....    84,  92 

Phospho-titanate,  insoluble 179 

Pichard,  determination  of   manganese   in 

steel  by  color  method 126 

Pipette,  Hempel's    composite,  method   of 

filling 291 

Hempel's  simple,  method  of  filling  291 

Plate,  chilled-iron,  and  muller 12 

Platinic  chloride  solution,  reagent  ....  57 

Platinum  apparatus 32 

combustion-tube  for  carbon  determi- 
nations in  iron  and  steel 154 

crucibles,  method  of  cleaning     ...  33 
filtering-tube    for   carbon    determina- 
tions in  iron  and  steel 157 

"  Policemen'' for  removing  precipitates     .  31 

Potassa,  caustic,  reagent  ........  47 

Potassa  and  soda,  separation  of 256 

Potassium,  bichromate  of,  reagent  ....  48 

bisulphate  of,  reagent 49 

chlorate  of,  reagent 48 

ferricyanide  of,  reagent 50 

ferrocyanide  of,  reagent 50 

iodide  of,  reagent 49 

nitrate  of,  reagent 48 


Potassium,  nitrite  of,  reagent 47 

permanganate  of,  reagent 50 

sulphide  of,  reagent 48 

Purifying  apparatus  for  oxygen  and  air  .    .  144 
Pyrogallate  of  potassium,  absorbent  power 

of 292 

Rack  for  permanent  standards  in  color  car- 
bon method 175 

Rapid  evaporations,  apparatus  for  ....  20 

Rapid  filtration,  Bunsen's  method  of  ...  24 

Gooch's  method  of 26 

Reagents 37 

for  determining  phosphorus      ....  58 

for  the  analysis  of  gases 291 

Reductor,  Jones's,  for  ferric  sulphate  solu- 
tions      209 

simple  form  of 95 

Regnault,  determination  of  carbon  in  iron 

and  steel 130 

Richards  injector 23 

Richter,  determination  of  carbon  in  iron 

and  steel 130 

Riley,   determination    of    titanium    in  pig- 
iron      178 

Rivot,  separation   of   alumina  and   ferric 

oxide 250 

Rubber  stoppers 32 

Safety-guard  tube  in  CO2  determinations  .  145 

Sampling  iron  ores,  method  of 205 

pig-iron,  method  of 1 6 

Sand-bath 19 

Shinier,  member  sub-committee  on  Stand- 
ard methods 95 

insolubility  of  carbide  of  titanium  in 

hydrochloric  acid 167 

Siemens's  producer  gas,  example  of  analy- 
sis of   302 

Silica,  determination  of,  in  iron  ores  .    239,  247 
Silica,  alumina,  lime,  magnesia,  oxide  of 
manganese,   and   baryta,   determination 

of,  in  iron  ores 238 

Silicon,  determination  of,  in  iron  and  steel  72 

by  solution  in  HNO3  and  HC1    .  72 

by  solution  in  HNO3  and  H2SO4  73 

by  volatilization  in  a  current  of 

chlorine  gas 73 


INDEX. 


321 


Silicon,  determination  of,  in  iron  and  steel, 

rapid  method,  by  Ford 77 

Slag,  basic,  analysis  of 279 

converter,  analysis  of 278 

decomposed  by  HC1,  analysis  of     .    .  276 
not    decomposed    by    HC1,    analysis 

of 278 

refinery,  analysis  of 278 

Slags,  methods  for  the  analysis  of  ....  276 
Slags  and  oxides,  determination  of,  in  iron 

and  steel 78 

by  solution  in  iodine     ...  79 
by  volatilization  in  a  current 

of  chlorine  gas 80 

Smith,  J.  L.,  determination  of  alkalies  in 

minerals      273 

Soda,  caustic,  reagent   .    .    .    . 46 

Soda  and  potassa,  separation  of 256 

Sodium,  acetate  of,  reagent 47 

carbonate  of,  reagent 46 

hyposulphite  of,  reagent 47 

nitrate  of,  reagent 46 

thiosulphate  of,  reagent 47 

Sodium  and  ammonium,  phosphate  of,  re- 
agent    46 

Sonnenschein,  determination  of  phosphorus 

in  iron  and  steel 89 

Spatulas,  platinum 34 

Specific  gravity  of  iron  ores,  method  of  de- 
termining      265 

Stand  for  holding  absorption  apparatus  for 
CO2  in  the  determination  of  carbon  in 

iron  and  steel 146 

Standard   solutions    for    determination    of 

iron,  proper  strength  of 222 

Standardizing  volumetric  solutions  for  de- 
termination of  iron  by  ferrous 

sulphate 222 

by  iron  wire 221 

by  solution  of  ferric  chloride   .    .  219 
Stead,  determination  of  combined  carbon  in 

low-carbon  steels  and  iron    ....  176 
determination  of  chromium   and   alu- 
minium in  iron  and  steel 191 

Stead's  chromometer 177 

method  for  low- carbon  steels    ....  176 
Stirring  machine  for  dissolving  steel  and 

iron  in  carbon  determinations  ....  149 


Sulphate  of  barium,  determination  of,  in 

iron  ores 228 

Sulphates,  soluble,  determination  of,  in  iron 

ores 228 

Sulphur,  conditions  of,  in  coal 286 

as  sulphides,  in  iron  ores 229 

determination  of,  in  iron  and  steel  by 

evolution  as  H2S 59 

by  evolution  as  H2S,  and  absorp- 
tion by  alkaline  solution  of  ni- 
trate of  lead 59 

by  evolution  as  H2S,  and  absorp- 
tion by  ammoniacal  solution  of 
sulphate  of  cadmium     ....      62 
by  evolution  as  H2S,  and  absorp- 
tion in  ammoniacal  solution  of 

nitrate  of  silver 62 

by  evolution  as  H2S  and  absorp- 
tion and  oxidation  by  bromine 

and  HC1 63 

by  evolution  as  H2S  and  absorp- 
tion and  oxidation  by  perman- 
ganate of  potassium 64 

by  evolution  as  H2S  and  absorp- 
tion and  oxidation  by  peroxide 

of  hydrogen 65 

by  oxidation  and  solution      ...      65 

by  rapid  method 68 

determination  of,  in  coal  and  coke  .    .    284 
determination  of,  in  pig-iron,  special 

precautions 66 

total,  determination  of,  in  iron  ores  .     226 
method  of  reporting  amount  of,  in 

coal 285 

Sulphuretted  hydrogen  gas,  apparatus  for 

generating 43 

Sulphuric  acid,  reagent 39 

Sulphurous  acid,  reagent 41 

Svanberg  and   Struve,  phospho-molybdate 
reaction 89 

Tartaric  acid,  reagent 40 

Tin,  determination  of,  in  iron  and  steel  .    .  197 
Titanic  acid,  determination  of,  in  clay    .    .  274 
determination  of,  in  iron  ores  .    .  231 
interference  of  P2O5  with  precipi- 
tation of 179 

iron  ores  containing 229 


21 


322 

Titanic  acid,  iron  ores  containing,  analysis 
of 

separation  of  from  P2O5    .... 

tests  for,  in  iron  ores 

Titan iferous  iron  ores,  method  of  recog- 
nizing   

Titanium,  determination  of,  in  iron  .  .  . 

by  precipitation 

by  volatilization 

Triangles  and  tripods  of  platinum  .... 

Tripods 

Tungsten,  determination  of,  in  iron  and  steel 

in  iron  ores 

rapid  method  for  determination  of, 
in  iron  and  steel 

Uehling,  apparatus  for  delivering  different 

volumes  of  HNO3 

apparatus  for  delivering  constant  vol- 
umes of  ferrous  sulphate  solution    . 
Ullgren,  determination  of   carbon  in   iron 
and  steel 


Vanadium,  determination  of,  in  iron   and 

steel 200 

determination  of,  in  iron  ores  ....  264 
Volhard,  determination  of   manganese   in 

iron  and  steel 118 

iron  ores 234 

Washing-bottles,  forms  of 30 

Watch-glasses,  balanced 36 


INDEX. 


244 
179 


230 

178 

178 

1 80 

34 

23 

198 

264 

199 


170 


Water-bath,  for  determination    of   hygro- 
scopic water  in  iron  ores      ....     206 
for  use  in   color  carbon  method  and 

color  manganese  method      ....     169 
Watts,  determination  of  silicon  in  iron  and 

steel     . 73 

Weyl,  determination  of  carbon  in  iron  and 

steel 130 

Whitfield,  apparatus  for  hastening  evapora- 
tions            20 

Williams,    method    for    determination    of 

manganese  in  iron  and  steel 120 

Wohler,  determination  of  carbon  in  iron 

and  steel 130 

separation  of  alumina  and  ferric  oxide     250 
Wood,  modification  of  color  carbon  method 

for  low  steels 172 

rapid    method    for    determination    of 

phosphorus  in  iron  and  steel    .    .    .     108 
use  of  HF1  in  steels  high  in  silicon 
and  pig-irons,  in   determination  of 
manganese 117 

Zimmerman,  determination  of  iron  in  iron 

ores 217 

Zinc,  determination  of,  in  iron  ores    ...  251 

metallic,  reagent 57 

amalgamated  for  use  in  reductor     .  loo 
powdered    for    reducing    molybdic 

acid 102 

oxide  of,  in  water,  reagent 58 


THE    END. 


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